University of Ilorin, also known as Unilorin, is a federal government-owned university in Ilorin, Kwara State, Nigeria. It was established by a decree of the federal military government in August, 1975. The establishment aimed to implement one of the educational directives of the Third National Development Plan which was aimed at providing more opportunities for Nigerians aspiring to acquire university education and to generate high-level manpower, so vital for the rapidly expanding economy. Compared to other higher institutions of learning in the country, the institution has one of the largest land areas, covering approximately 15,000 hectares of land. It is revealed by JAMB to be the most sought after university in the year 2021.
Residual stresses formed during quenching can significantly impact the integrity of engineering components. This study examined how varying immersion speeds in water affected both mechanical behavior and residual stress distribution in SAE 1025 steel. To achieve this, a hybrid approach combining finite element simulations (using ANSYS 2020 R1 and JMatPro) with controlled laboratory experiments was employed. The immersion speed control mechanism was developed and calibrated. Steel samples were quenched at five immersion speeds, ranging from 0.05 to 0.8 m/s. Metallographic analysis, Vickers microhardness testing and tensile testing were assessed and then compared to simulation predictions. A significant finding was the 83% reduction in maximum residual stress as immersion speed increased from 0.2 to 0.8 m/s. Furthermore, residual stress was significantly lower at the leading (first-contact) end of each sample and higher at the trailing end. Simulation results showed strong agreement with experimental findings, achieving an average error of 7.5% across the temperature range and a correlation coefficient (R2) of 0.97. Ultimately, the prediction of residual stress distributions achieved in this study will enable the production of safer and more durable components, critical for demanding engineering applications where performance and integrity are non-negotiable.
Brake pads in automobiles are crucial, since their effectiveness determines the safety of vehicles in operation. Alternatives for brake pad liners are continuously being researched as a way of replacing detrimental materials such as asbestos and graphite. This research was aimed at developing some eco-friendly brake pad liners with agro-residue materials. The brake pad liners were produced using compression moulding employing particle sizes of three different sieve ranges of 400-300, 300-250 and 400-00 & micro;m. The composite materials for brake pad liners production included seashell, sawdust, palm kernel shell (PKS) and charcoal, serving the functions of structural, filler, abrasive and lubricant, respectively, while the binder used to hold the composite together was epoxy resin (polyepoxide) mixed with hardener (diethylenediamine) in 2:1 ratio. Microstructural analysis conducted on three samples, formulated based on selected sieve ranges, displayed the composite arrangement in the formulation, and the effect of particle sizes. Sample C (400-00 & micro;m) displayed an evenly distributed and closely packed particle sample. Results revealed that hardness of the composite material decreased with smaller sieve ranges. Sample C, with the compressive strength of 4.0839 MPa, had lowest hardness value and highest thermal stability of 394 degrees C, with corrosion rate of 0.0056 mm/yr.
Perfluorooctanesulfonic acid (PFOS), a persistent and bioaccumulative substance, has emerged as a major environmental contaminant of global concern. PFOS, widely used in industry and consumer products, is common in aquatic ecosystems and may harm primary producers like phytoplankton, though its effects on their community structure and physiology remain unclear. Here, we investigated the impact of PFOS on freshwater physicochemical parameters, phytoplankton community dynamics, biochemical composition, and oxidative stress responses in a mesocosm experiment over a 28-day period. The water quality indicators generally were unaltered by PFOS exposure, but phosphate levels decreased initially in the control. Phytoplankton biomass (cell density) decreased at 10 µg L−1 and 10 mg L−1 PFOS exposures. Phytoplankton species richness, Shannon, and Simpson diversity indices declined at 10 mg L−1, with communities at this concentration becoming distinctly different from the control and lower PFOS treatments by day 28. This shift in community structure was primarily driven by taxa such as Chlorogonium sp. and Microcystis aeruginosa, which contributed strongly to the observed compositional dissimilarity. Proteins content in the phytoplankton increased under PFOS exposure, peaking on day 21. In contrast, carbohydrate and lipid contents were reduced under PFOS relative to the control. PFOS exposure elevated glutathione-S-transferase activity, malondialdehyde, and hydrogen peroxide levels, whereas peroxidase activity was reduced. The phytoplankton biomass and lipids were positively associated, while oxidative stress markers were closely linked with high PFOS concentrations. Overall, these results highlight that PFOS exposure suppressed phytoplankton biomass, altered their community composition, and induced oxidative stress and metabolic shift at higher concentrations, highlighting its potential ecological risk in freshwater systems.
The dimensional analysis of the position and momentum variances-based quantum mechanical Heisenberg uncertainty measures was carried out for generalized Yukawa-type potential. The entropic information measures given by Shannon entropy sums and Fisher information products were obtained out for generalized Yukawa-type potential. It is interesting to observe that the Shannon entropy in position space, , increases and then decreases with the quantum number , suggesting a growth in delocalization due to a rapid increase in fluctuations. Likewise, the Shannon entropy in momentum space, , decreases and then increases with the quantum number , and vice versa. This unusual phenomenon may be explained by the parity restrictions inherent in the system. The Bialynicki-Birula and Mycielski (BBM) entropic uncertainty relation was verified to be saturated; however, the sum of the entropies increases with the quantum number up to a certain point and then decreases as continues to increase. We also found that the Fisher information accurately increases with the quantum number . The numerical results that support the validity of the scaling properties for Shannon entropy sum and Fisher information product were presented. The existence of a squeezed phenomenon in the ground and first excited state for some values of the potential screening parameter in momentum space was found. The Heisenberg uncertainty relation is met when the squeeze in one coordinate is compensated by an increase in the other coordinate. The results obtained exceed the theoretical lower bounds for all the information-theoretic measures considered, confirming their physical validity and accuracy.
Abstract This study investigates the surface morphology, microhardness, and electrochemical corrosion behavior of Ti-Mn alloys reinforced with hydroxyapatite (HA) at 5, 10, and 15 wt% concentrations, fabricated via spark plasma sintering (SPS), in 0.9 wt% and 3.5 wt% NaCl solutions. Scanning electron microscopy (SEM) revealed a dense Ti-10Mn microstructure with polygonal α-Ti grains and needle-like titanium-manganese intermetallic phases, while higher HA content increased particle aggregation, porosity, and microvoids. The microhardness of titanium increased from 229 HV0.3 to 352 HV0.3 with manganese addition due to β-Ti phase formation and lattice strain. Further reinforcement with 5, 10, and 15% hydroxyapatite raised the values to 543, 657, and 710 HV0.3, respectively, by limiting dislocation motion through particle strengthening. Electrochemical tests, including potentiodynamic polarization and electrochemical impedance spectroscopy (EIS), were employed to evaluate the corrosion performance. Pure Titanium showed superior corrosion resistance due to the formation of a stable TiO2 passive layer. Mn addition, increased corrosion susceptibility, whereas 10 wt% HA significantly enhanced corrosion resistance, with the lowest corrosion current density (I corr = 9.261 µA/cm² in 0.9 wt% NaCl; 6.868 µA/cm² in 3.5 wt% NaCl). EIS analysis, using Nyquist and Bode plots with a constant phase element (CPE) model, confirmed the 10 wt% HA composite’s highest polarization resistance (R p = 5.46E + 05 Ω·cm² in 0.9 wt% NaCl; 5.10E + 05 Ω·cm² in 3.5 wt% NaCl) and near-ideal capacitive behavior (α = 0.954 and 0.955), indicating a strong passive film. The 15 wt% HA composite exhibited reduced polarization resistance (R p = 1.13E + 03 Ω·cm² in 0.9 wt% NaCl) due to porosity and HA clustering. These results highlight the optimal HA content for Ti-Mn composites in biomedical and structural applications.
