Physical Science International Journal

Green Corrosion Inhibitors for Mild Steel in Sulphuric Acid: Performance Evaluation of PEG (Polyethylene Glycol) and Alkali-Treated Starch Blends

2026-06-01T13:16:33+00:00

The corrosion inhibition performance of native starch (NS), alkaline-modified starch (MS), polyethylene glycol (PEG), and their blends on mild steel in acidic medium was evaluated using weight loss measurements over 120 h. Single inhibitors exhibited moderate inhibition efficiency at 24 h, with PEG showing the highest initial performance, but all single systems experienced a decline in efficiency with increasing exposure time due to desorption. Adsorption behavior at 24 h followed the Langmuir isotherm with R² > 0.99 for all inhibitors, indicating monolayer adsorption. Calculated adsorption equilibrium constants followed the trend NS > MS > PEG, while standard free energy values ranged from −19.6 to −20.8 kJ/mol, suggesting mixed physisorption and chemisorption mechanisms. Synergy analysis revealed that most blends exhibited antagonistic behavior at 24 h due to competitive adsorption. However, the 0.1 g/L MS + 0.4 g/L PEG blend developed strong synergy over time, with a synergy parameter of 1.64 at 120 h and inhibition efficiency increasing from 46.4% to 89.5%. This indicates that MS pre-adsorbs on the steel surface and facilitates the formation of a stable PEG protective film, leading to sustained corrosion inhibition. The results demonstrate that strategic blending of inhibitors with complementary adsorption properties can provide effective long-term corrosion protection in acidic environments.

Geomagnetic Activity and Energy Dynamics of the Inner Magnetosphere During Solar Cycle 24

2026-06-05T10:24:43+00:00

Solar wind–magnetosphere coupling governs the transfer of energy from the solar wind into the Earth's magnetosphere and plays a fundamental role in space weather processes. This study investigates the occurrence of different geomagnetic activity classes defined by Legrand & Simon (1989) and quantifies the power transferred to the inner magnetosphere during Solar Cycle 24 (2008–2018). Solar wind and interplanetary magnetic field data were analyzed using the coupling function proposed by Wang et al. (2014) to estimate the energy input into the inner magnetosphere. The variability of the parameter E_inis studied during periods of disturbed geomagnetic activity in comparison with quiet periods; the B_Zcomponent of the IMF, the clock angle and the dynamic pressure. We also use pixel diagrams to study the occurrences of different days of geomagnetic activity. The results show that quiet days dominated Solar Cycle 24, accounting for approximately 73% of the observed period, whereas disturbed conditions represented about 27% of days. The distribution of disturbed days in terms of geomagnetic activity is as follows: 25.03% fluctuating days, 1.42% recurrent days and less than 1% shock days. This strong predominance of quiet days indicates the generally calm state of the magnetosphere during Solar Cycle 24. The highest frequencies of calm days are recorded at the phase minimum; those of shock days, recurrent days and fluctuating days during the descending phase. Furthermore, from the phase minimum to the descending phase, the frequency of calm days decreases continuously, falling from 84.81% at the phase minimum to 62.90% in the descending phase. The perfectly in-phase diurnal variations between the power transferred to the inner magnetosphere during shock days and fluctuating days, and the geometric efficiency of solar wind–magnetosphere coupling, suggest that the clock angle is the parameter that directly controls the transfer of energy from the solar wind to the inner magnetosphere on days of geomagnetic activity during such events. The average power transmitted to the inner magnetosphere is minimal during quiet days (316 GW) and maximal during shock activity days (4864 GW). The average power transmitted during recurrent days (2518 GW) is approximately double that transmitted during fluctuating days (1200 GW). Regardless of the nature of the disturbance, the power transmitted to the inner magnetosphere during disturbed periods is 1800 GW. The power transmitted to the inner magnetosphere is correlated with the Aa geomagnetic index, estimated from the level of disturbance in the geomagnetic field caused by solar activity.

Assessment of the Potentially Toxic Elements (PTEs) Contamination of Date Fruits (Phoenix dactylifera L.)

2026-06-24T06:33:57+00:00

Potentially toxic elements (PTEs) in food products represent a public health concern because of their persistence, bioaccumulation potential and adverse effects. This study assessed the contamination levels and potential health risks of selected PTEs in date fruits (Phoenix dactylifera L.) obtained from a major market in Gwagwalada, Federal Capital Territory, Abuja, Nigeria. A total of approximately 50 kg of date fruits was collected, prepared under standard laboratory conditions and analysed in triplicate (n = 3). The concentrations of chromium (Cr), lead (Pb), arsenic (As), cadmium (Cd) and thallium (Tl) were determined using Atomic Absorption Spectrophotometry. Data were expressed as mean ± standard error of the mean, and statistical analysis was performed to evaluate differences among the measured concentrations. The mean concentrations were 27.16 ± 1.63 mg/kg for Cr, 3.95 ± 1.03 mg/kg for Pb, 0.54 ± 0.14 mg/kg for As, 0.47 ± 0.21 mg/kg for Cd and 0.15 ± 0.13 mg/kg for Tl. Chromium had the highest concentration, whereas thallium had the lowest. The concentrations of the investigated PTEs differed significantly (p < 0.05). The estimated daily intake, target hazard quotient (THQ) and hazard index (HI) were used for human health risk assessment. The THQ values for Cr, Pb, As, Cd and Tl were 15.09, 13.16, 3.00, 0.70 and 3.12, respectively. All metals except Cd had THQ values greater than 1, indicating potential non-carcinogenic health risks. The cumulative HI was 35.07, which exceeded the safety threshold of 1. Comparison with FAO/WHO permissible limits showed that all measured metals exceeded their corresponding reference limits for food commodities, suggesting considerable contamination. These findings indicate the need for routine monitoring and stricter quality control of date fruits marketed in the study area.

Relationship between Solar Flare Classes and Halo Coronal Mass Ejection Occurrence: Effects of Speed and Angular Width during Solar Cycles 23-24

2026-06-30T12:46:14+00:00

This study examines the statistical relationship between solar flare classes and the occurrence of associated coronal mass ejections (CMEs) during solar cycles 23 and 24, covering the period from 1 January 1996 to 31 December 2019. The analysis considers CME angular width and speed, with CMEs grouped into narrow, normal, partial-halo, and full-halo categories. A total of 396 flare-associated CME events were considered, including 236 events during solar cycle 23 and 160 events during solar cycle 24. Among these events, 1 was associated with an A-class flare, 23 with B-class flares, 110 with C-class flares, 176 with M-class flares, and 86 with X-class flares.

The results show that M-class flares were the most frequently associated flare class across the CME categories. Narrow CMEs were mainly associated with M-class flares, while normal CMEs showed a broader distribution involving C-, M-, and X-class flares. Partial-halo CMEs were the dominant angular-width category in the dataset and were mostly associated with M-, C-, and X-class flares. No full-halo CME with an angular width of 360° was recorded in the analysed sample.

The speed distribution indicates that CMEs associated with M- and X-class flares were more frequently represented in higher-speed ranges, including events above 1500 km/s and, in some cases, above 2200 km/s. In the narrow-CME subset, the few X-class flare associations occurred only in the higher-speed categories. Overall, the results suggest that CME angular width alone does not determine CME speed or the intensity class of the associated solar flare. The findings should therefore be interpreted as a descriptive statistical assessment of flare-associated CME properties, while direct evaluation of CME geoeffectiveness would require additional in situ solar-wind and geomagnetic-response data.

Electrical Characterization of a Mechanized Pilot Cassava Processing Unit Installed in Ouagadougou: Case of No-Load Operation

2026-06-30T13:41:23+00:00

Cassava processing is commonly performed with manual tools such as knives, machetes and mortars, making the operation laborious and time-consuming. Mechanised processing units can reduce this workload, but their electrical requirements must be characterised to support efficient operation and energy planning. This study evaluated the no-load electrical behaviour of a mechanised pilot cassava processing unit installed in Ouagadougou. The unit comprised four main items of equipment: a washer, a peeler, a grater and a spin dryer, each driven by a three-phase low-voltage asynchronous motor. Electrical measurements were conducted under no-load conditions for 60 minutes, with measurements taken at 5-minute intervals. The two-wattmeter method was used to determine voltage, current, active power, reactive power, apparent power and power factor. The results showed that the average active power values of the peeler, washer, grater and spin dryer were 328 W, 762 W, 1005 W and 4506 W, respectively. The corresponding average power factor values were 0.98, 0.98, 0.83 and 0.82. The spin dryer had the highest no-load energy demand and consumed approximately 4.5 kWh during one hour of operation, whereas the peeler consumed approximately 0.3 kWh. Reactive power was nearly zero for the washer and peeler, approximately -1000 VAr for the grater and between 2000 VAr and 4000 VAr for the spin dryer. These findings provide a baseline for understanding idle operation and identifying equipment with higher no-load energy demand.

Influence of Magnetic Field and Temperature on the Charge Carrier Transport Parameters in a Radial Junction Solar Cell

2026-06-30T14:23:23+00:00

This study examines the combined influence of magnetic field and operating temperature on charge-carrier transport parameters in a polycrystalline silicon radial junction solar cell. The analysis focuses on carrier mobility, diffusion coefficient, and diffusion length, which are central to the collection of photogenerated carriers and the photovoltaic performance of the device. The results indicate that increasing temperature reduces carrier mobility because of stronger carrier–phonon interactions. This reduction in mobility also decreases the diffusion coefficient and diffusion length, thereby limiting the ability of charge carriers to reach the junction before recombination. The applied magnetic field also affects transport behaviour through the Lorentz force, which deflects carriers from their initial trajectories and reduces their effective mobility and drift velocity. At low magnetic fields, below 10⁻⁴ T, the diffusion coefficient and diffusion length remain nearly constant. In the intermediate range of 10⁻⁴ T to 10⁻² T, both parameters decrease progressively, while for magnetic fields above 10⁻² T, strong carrier confinement produces a marked limitation of transport. The maximum diffusion length is approximately 20 µm near room temperature, around 300 K, in the absence of a magnetic field or under very weak magnetic fields. These findings indicate that a base radius close to 20 µm is suitable for improving carrier collection in the studied radial junction configuration.

Evaluation of Heavy Metal Pollution Levels in Agricultural Soils Around the Kalsaka Gold Mine, Burkina Faso

2026-07-03T13:39:29+00:00

This study evaluated heavy metal pollution levels in agricultural soils around the Kalsaka gold mine in Burkina Faso. Sixteen surface soil samples were collected from agricultural areas near the former mining site and analysed for chromium, nickel, copper, zinc, arsenic, mercury, and lead. The soil samples were sieved, digested using aqua regia, and analysed by atomic absorption spectrophotometry. Soil contamination was assessed by comparing concentrations with reference limits and by calculating the contamination factor, Pollution Load Index, and geo-accumulation index. The mean concentrations of the analysed metals were 206.56 mg/kg for chromium, 52.68 mg/kg for nickel, 132.82 mg/kg for copper, 129.24 mg/kg for zinc, 276.94 mg/kg for arsenic, 5.13 mg/kg for mercury, and 44.22 mg/kg for lead. The average concentrations followed the order As > Cr > Cu > Zn > Ni > Pb > Hg. Chromium, nickel, copper, arsenic, and mercury exceeded the reference limits used in the study, whereas zinc and lead remained below the corresponding limits based on mean values. Arsenic and mercury had the highest contamination factor and geo-accumulation index values, indicating that they were the main contributors to soil pollution in the study area. Pollution Load Index values were greater than one for all sampled soils, showing that the agricultural soils around the Kalsaka mine were affected by heavy metal contamination. The findings indicate degraded soil quality in the study area and highlight the need for continued monitoring, improved environmental management, and further assessment of metal mobility and potential transfer into crops.

Modeling and Experimental Analysis of a Dual-collector Indirect Solar Dryer for Intermittent and Continuous Drying of Bioproducts

2026-07-09T06:46:22+00:00

This study presents the development and experimental validation of a coupled heat and mass transfer model for a dual-collector indirect solar dryer based on the energy balance of a representative section of the system. The governing equations describe the simultaneous evolution of collector temperature, drying air temperature and product moisture content while accounting for solar irradiance variations of up to 1050 W m⁻², convective heat transfer and both continuous and intermittent drying modes. Experimental tests were conducted on banana (Musa paradisiaca) and sweet potato (Ipomoea batatas), with a loading capacity of 1.5 kg for each product and an intermittency ratio of α = 0.5 under a controlled drying temperature below 60 °C. Temperature profiles, dry-basis moisture content and drying rates were determined and analysed for both operating configurations. The results showed favourable thermal conditions for drying, characterised by a gradual increase in temperature and enhanced mass transfer during the initial drying stage. Moisture content decreased from approximately 1.4 to 1.2 kg water kg⁻¹ dry matter for banana and from 3.0 to 2.6 kg water kg⁻¹ dry matter for sweet potato, indicating rapid evaporation of free water. Maximum drying rates of 5.6 and 6.3 kg water kg⁻¹ dry matter min⁻¹ were recorded for banana and sweet potato, respectively, demonstrating the intensity of heat and mass transfer at the beginning of the process. Comparison of continuous and intermittent drying modes showed that intermittency reduced the overall drying rate while stabilising thermal and moisture gradients. Numerical predictions were in good agreement with experimental observations, confirming the reliability of the proposed model. The observed discrepancies were mainly attributed to climatic fluctuations and simplifying assumptions adopted in the model.

Ground-Level Enhancement 77 of 11 November 2025: Relativistic Solar-Particle Acceleration, an Extreme Geomagnetic Storm, and Forbush Decreases Driven by Solar Active Region 4274

2026-07-10T13:36:32+00:00

The rising phase of Solar Cycle 25 has produced several extreme space-weather episodes driven by explosive magnetic reconnection in the solar atmosphere. This study presents an integrated, multi-parameter analysis of the eruptive sequence of 9–14 November 2025 originating from the magnetically complex active region NOAA AR 4274, focusing on the X5.1 flare of 11 November 2025 (peak 10:04 UT). This flare accelerated solar protons to relativistic (>1 GeV) energies and produced the Ground-Level Enhancement (GLE) catalogued as GLE #77, recorded by the global neutron-monitor network from ~10:15 UT and now established as the strongest GLE in 19 years. Using daily sunspot number and F10.7 cm flux (Royal Observatory of Belgium/SIDC and DRAO), hourly interplanetary magnetic field (IMF) and solar-wind plasma data (NASA OMNIWeb), geomagnetic indices (Kp, Dst, SYM-H), and pressure-corrected neutron-monitor count rates (Oulu and the global network via gle.oulu.fi and NMDB), this study traces the complete Sun–heliosphere–Earth chain over 8–17 November 2025. GLE #77 reached peak amplitudes of about 125% in standard neutron monitors and 165% in bare neutron monitors globally, with pronounced rigidity dependence (e.g., ~102% at South Pole, ~25% at high-latitude and ~9–21% at mid-latitude stations) and a complex, anisotropic, dual-peak time profile. The associated compound shock–ICME structure drove a severe geomagnetic storm (Kp = 9−; Dst ≈ −231 nT; SYM-H ≈ −254 nT), with the main phase occurring early on 12 November, accompanied by sustained southward IMF Bz and elevated solar-wind speed. The relativistic-particle enhancement was followed by Forbush decreases in galactic cosmic-ray intensity. Placed in the context of recent GLEs (GLE 69–GLE 73), GLE #77 emerges as the hardest and strongest relativistic solar-particle event since GLE 70 (2006). The results illustrate the dual role of major eruptions in both accelerating relativistic particles and modulating galactic cosmic rays and provide a benchmark event for space-weather forecasting during Solar Cycle 25.

Seismic Tomography for Crustal Imaging Beneath Nsukka, Ife, and Kaduna Seismic Stations in Nigeria

2026-07-11T04:21:14+00:00

This study investigates crustal structure beneath the Nsukka, Ife, and Kaduna seismic stations in Nigeria using waveform data from the 11 September 2009 earthquake recorded by the national seismic network. The work applies body-wave phase modelling to examine P- and S-wave propagation and to estimate selected crustal parameters beneath the three recording stations. The analysis used available station coordinates, earthquake source parameters, processed waveform records, and a global crustal velocity model as an initial reference model. Seismic wave arrivals and phase conversions were examined to estimate Moho depth and to derive compressional-wave velocity, shear-wave velocity, and Vp/Vs ratio from slowness values. The results indicate variable crustal thickness beneath the investigated stations, with estimated Moho depths of approximately 35 km beneath Ife, 39 km beneath Kaduna, and 29 km beneath Nsukka. The shallower Moho estimate beneath Nsukka may reflect crustal thinning associated with the sedimentary and tectonic setting of southeastern Nigeria, whereas the deeper estimates beneath Ife and Kaduna are consistent with their basement-complex settings. The 2009 earthquake source depth indicates a shallow crustal event. The derived Vp, Vs, and Vp/Vs values provide preliminary constraints on crustal properties beneath the stations and are broadly useful for improving regional crustal characterisation. The study demonstrates the value of local earthquake waveform records for crustal investigation in Nigeria, while also emphasizing the need for a denser seismic network and a locally calibrated velocity model to improve future seismic hazard assessment and subsurface interpretation.

Evaluation of Electromagnetic Field Exposure 250 m around a Base Transceiver Station in Owa-Eke Delta State, Nigeria

2026-07-11T10:44:01+00:00

The increasing deployment of mobile communication infrastructure has raised public concern regarding exposure to radiofrequency (RF) electromagnetic fields around base transceiver stations (BTSs). This study evaluated electromagnetic field exposure around a BTS in Owa-Eke, Delta State, Nigeria, using field measurements collected over a 90-day monitoring period. Electric field strength, magnetic field strength and power density were measured with a Tenmars RF meter at the study location, and the recorded values were analysed using descriptive statistics. The tabulated measurements showed electric field strength values ranging from 45.74 to 100.64 V/m. Magnetic field strength values ranged from 128.63 to 389.75 mA/m, while power density values ranged from 9.24 to 27.57 W/m², although the highest value appears as an isolated entry in the dataset and requires verification. Based on the 90 daily values presented in Table 1, the recalculated mean values were approximately 72.81 V/m for electric field strength, 235.70 mA/m for magnetic field strength and 17.89 W/m² for power density. The results indicate measurable temporal variation during the monitoring period. Comparison with public exposure reference levels showed that some recorded values were above the stated limits. These findings suggest that exposure assessment around the studied BTS should be interpreted cautiously and supported by verification of measurement units, instrument calibration, averaging procedures and possible data-entry errors. Periodic monitoring is recommended to provide more reliable evidence on exposure patterns around telecommunication infrastructure in the study area.