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Synthesis and Characterization of As-Synthesized Co-deposited PbS/ZnS Thin Films Prepared by SILAR Technique
Thin-film semiconductors are widely studied for their applications in various optoelectronic devices. PbS and ZnS are useful semiconductors for various optoelectronic applications, with PbS having low energy bandgap while ZnS has wide energy bandgap. In this paper, we investigate the structural, morphological, optical and electrical properties of the as-synthesized PbS/ZnS films and evaluate their potential in optoelectronic applications. PbS/ZnS thin film was synthesized using the Successive Ionic Layer Adsorption and Reaction (SILAR) method, by varying deposition cycles without post-deposition annealing. The X-ray diffraction (XRD) peaks confirmed the presence of cubic phases of PbS and ZnS with increasing crystallinity at higher SILAR cycles. Scanning electron microscopy (SEM) revealed enhanced surface coverage and grain growth with increased cycles while energy disperse X-ray spectroscopy (EDS) verified the presence of Pb, Zn and S. Optical bandgap energies ranged from 1.43 eV to 2.82 eV, which is attributed to changes in film thickness and composition. Hall Effect showed n-type conductivity with varying carrier concentration and mobility. These results highlighted the tunability of PbS/ZnS thin films via SILAR cycles, making them promising for application in solar cells and photodetectors.
Copyright (c) 2025 Journal of Science and Technology
Comparative Assessment of Drinking Water Quality: An Investigation of Physicochemical and Microbial Characteristics
Water pollution has been the major challenges in Nigeria. The consumption of contaminated water threatens the health and livelihoods of citizens. The study assesses the suitability of drinking water sources in Ikot Ekpene metropolis using physiochemical and microbial characteristics. Water samples were collected monthly between April 2023 and November 2023 in six drinking water sources; the samples were analyzed using standard laboratory techniques. The results revealed that the mean value of NO2 in sachet and surface water and the pH value in surface water were deviated from Nigerian drinking water quality standard. The THBC values in sachet water ranged between 1.0 and 3.0 cfu/100mL, while surface water ranged between 24.0 and 167.0 cfu/100mL; the TCC ranged from 0.0 to 2.0 cfu/100mL in sachet water and 12.0 to 66.0 cfu/100mL in surface water; the TSBC ranged from 5.0 to 17.0 cfu/100mL in sachet water and 5.0 to 59.0 cfu/100mL in surface water, while TFCC values in sachet water ranged from 0.0 to 3.0 cfu/100mL and 6.0 to 50.0 cfu/100mL in surface water. The mean values of TSBC and TFCC (sachet water) and THBC, TCC, TSBC, TFCC (surface water) exceeded the limits for Nigerian drinking water quality. The Clostridium spp was the most abundant in surface water, while Staphylococcus spp was in sachet water samples. The WQI value was higher (67.0) in surface water compared with the 5.58 recorded in sachet water. The study revealed that the surface water is polluted compared with the sachet water, and not suitable for human consumption, owing to the prevalence of microbial parameters attributed to anthropogenic activities.
Quantification of Perfluorooctanesulfonic Acid in Human Serum Using Triple Quadrupole Liquid Chromatography‒Mass Spectrometry
Perfluorooctanesulfonic acid (PFOS), a persistent organic pollutant, has an unclear association with metabolic syndrome (MetS), particularly in Southeast Asian populations. Given the lack of PFOS detection in Malaysia, this study's rationale was to develop a simpler, faster, and cost-effective analytical method. We developed and validated a simple, sensitive LC-MS/MS method for PFOS quantification in human serum. The method employed an optimized Liquid-Liquid Extraction (LLE) using formic acid, acetonitrile, and n-hexane. PFOS and its internal standard were quantified using LC-MS/MS 6490 QQQ in multiple reaction monitoring (MRM) mode. The assay showed high specificity, acceptable precision, accuracy, and recovery, with a linear calibration range of 20–500 ng/mL. The validated method was used to determine PFOS level in serum from 40 healthy controls and 40 MetS patients. PFOS was detected in four MetS samples but not in any control samples. However, no significant difference was observed between the two groups (p-value = 0.1156). A sensitive and robust LC-MS/MS method for PFOS quantification was successfully developed. The preliminary detection of PFOS in a subset of MetS patients, even without statistical significance, highlights the need for larger cohort studies and further investigation into individual MetS components to fully elucidate any potential association.
Design, Simulation, and Performance Analysis of X-Band Patch Array Antenna for Car-Speed Detection Radar
The antenna is an essential component that plays important role in radar target detection and parameter estimation. This paper presents the design and simulation analysis of X-band patch array antenna for car-speed detection and monitoring radar system. A patch array antenna was designed at a center operating frequency of 10 GHz. The designed patch array antenna was simulated with a Computer Simulation Technology (CST) Microwave-Studio to analyze the antenna radiation pattern and other broadband properties. A compact and light-weight X-band 4×4 patch array antenna was realized on RT/Duroid 5880 copper board with 1.6 mm thickness and dielectric constant of 2.2. The patch array antenna shows high gain and good radiation characteristics with a simulated gain of 19.35 dBi, and corresponding radiation efficiency of 89.02%. The fabricated antenna was experimentally characterized and tested for real-world car-speed detection radar system. The studied patch array antenna demonstrates impressive performance suitable for radar applications.
Synthesis and characterization of a H-bonded charge-transfer complex formed between 1,10-phenanthroline monohydrate with some π-acceptors in different solvents
The charge-transfer complexes of the 1,10-phenanthroline monohydrate with m-dinitrobenzene, p-hydroxybenzoic acid, 3,5-dinitrosalicylic acid, and 3,5-dinitrobenzoic acid have been prepared and characterised by using different techniques like the 1H NMR, TGA-DTA, XRD, and FT-IR Fluorescence and Conductivity data indicate a charge-transfer interaction and as far as complexes are concerned, this interaction is associated with a H bonding and the transfer of H+ from the acceptor to the donor molecules. The FT-IR and 1H NMR spectroscopic data also indicated a charge-transfer interaction associated with a proton migration from the acceptor to the donor followed by intermolecular H bonding.
AI-Based Social Assistance for Children with Neuropsychiatric Disorders: Enhancing Social Behavior and Interaction
Children diagnoses with conditions such as ADHD or autism have difficulty with social interaction and managing emotions. These difficulties make traditional therapy inefficient. In this study, we will introduce artificial intelligence (AI) and see how it will support these children in developing better social skills. Hence, we present a tool called Spark Humanoid; an agent that uses AI to give kids feedback based on their facial expressions and how they respond during fun, and game session. The system uses convolutional neural network (CNNs) to understand the child’s emotions and applies the A* algorithm in puzzle games to offer helpful hints and adjust difficulty as needed. We tested the tool during therapy sessions with support from the Palestine Childhood Institute. The system shows promising results, since kids seemed more engaged and responded more positively when using the AI tool compared to traditional sessions. These results shows that AI could be a useful addition to therapy, giving us new ways to help children with neuropsychiatric challenges.
Neuropsychiatric Disorders, ADHD, Autism, Artificial Intelligence, Emotion Recognition, Pediatric Therapy
Artificial Intelligence; Human-Computer Interaction; Assistive Technology; Health Informatics; Neurodevelopmental Disorders
Object Detection in Self-Driving Vehicle Using CARLA Simulator and YOLOv8
This study develops an object detection system for autonomous vehicles using the YOLOv8 model integrated with the CARLA simulator. The research addresses gaps in multi-camera setups and real-time detection by training YOLOv8 on a custom dataset generated from CARLA simulations. Results show high performance with a mean Average Precision (mAP@50) of 0.990 in single-camera configurations, outperforming multi-camera setups due to computational constraints. While Proportional-Integral-Derivative (PID) and Model Predictive Control (MPC) integration was explored conceptually, empirical evaluation revealed enhanced navigation accuracy in simulated scenarios, though real-world validation is needed. The work highlights trade-offs between accuracy and speed, suggesting optimizations for practical deployment.
Investigation of Prunus domestica Leaves Aqueous Extracts as a Sustainable Solution for Corrosion Control of Carbon Steel in 1M HCl: Thermodynamic, Adsorption and Electrochemical Insight
This study investigates the efficacy of Prunus domestica leaves aqueous extract (PDLAE) as a sustainable corrosion inhibitor for carbon steel in 1M hydrochloric acid solution. The research aligns with green chemistry principles, addressing the environmental concerns associated with the use of synthetic inhibitors. Comprehensive analyses, including weight loss assays, electrochemical measurements, adsorption isotherms, contact angle determination, and UV-visible spectroscopy, were conducted to evaluate the extract's corrosion inhibiting performance. The results revealed that the extract achieved a maximum inhibition efficiency of 92.07% at 2.0 g·dm⁻³ concentration after 24 hours, with thermally stable adsorption observed at high temperatures. Adsorption obeys the Langmuir model, indicating monolayer formation, and negative Gibbs free energy values (ΔG0ads ˃-20 kJ·mol-1) confirm spontaneous adsorption. Electrochemical tests demonstrated mixed-type inhibition behavior, reducing corrosion current density and enhancing charge transfer resistance. Additionally, the extract improved surface hydrophobicity, as evidenced by increased contact angles. FTIR analysis identified the presence of key phytoconstituents bearing hydroxyl and carbonyl functional groups and aromatic structures that contribute to corrosion inhibition efficiency. Obtained results highlight the PDLAE's potential as an eco-friendly and effective solution for metal protection and the importance of plant-based inhibitors in advancing environmentally benign corrosion prevention strategies.
Adsorptive Removal of Crystal Violet from Aqueous Solution Using Banana Pseudo Stem Biochar: Batch Adsorption Study
Synthetic dyes, such as crystal violet (CV), are extensively employed in many industries and contribute major environmental risks when released into water bodies. Agricultural waste biochar has been investigated for dye removal; however, studies on banana pseudo stem (BPS) biochar are limited. In particular, studies using BPS biochar produced at higher pyrolysis temperatures are scarce. Therefore, this study explores the adsorptive removal of BPS biochar produced through slow pyrolysis at 500°C for 1 h, a temperature selected to enhance the surface area and porosity for the removal efficiency of CV from aqueous solution. The effects of operating adsorption parameters, such as solution pH, biochar dosage, initial dye concentration, contact time and temperature, were assessed by batch adsorption experiments. The maximum CV percent removal of 96.9% with 4.85 mg/g of adsorption capacity was achieved at optimal conditions of pH 6, 0.4 g of biochar dosage, an initial CV concentration of 20 mg/L, 90 min of contact time, and at the temperature of 35°C. For the adsorption isotherm study, the experimental results were better fitted to the Langmuir model with a maximum adsorption capacity of 23.09 mg/g. Meanwhile, the kinetic study was found to be best fitted to the pseudo-second-order model. BPS biochar prepared at elevated pyrolysis temperature is a sustainable and efficient alternative to conventional adsorbents. The remarkable removal efficiency under mild conditions, combined with using agricultural waste as adsorbent feedstock, demonstrates the BPS biochar for practical use in dye-contaminated wastewater treatment.
Taming the Turbulence: Modelling and Forecasting Crude Oil Price Volatility with GARCH and SARIMA Models
The volatility is a signal of risk, either good or bad, to investors. Crude oil price is a commodity of global concern because its volatility significantly affects the economic stability of many countries. Due to the lack of comparative studies in forecasting performance, this study aims to model and forecast crude oil prices and their volatility by comparing the Generalised Autoregressive Conditional Heteroskedasticity (GARCH) model and the Seasonal Autoregressive Integrated Moving Average (SARIMA) model. The monthly crude oil price data from January 2000 to December 2019, obtained from the U.S. Energy Information Administration, are used for this analysis. The results show that the GARCH(3,1) model is the most suitable model compared to EGARCH, TGARCH, and SARIMA in capturing the volatility of crude oil prices. This indicates that the GARCH(3,1) model offers superior forecasting performance and can serve as a reliable tool for investors and policymakers to anticipate market fluctuations and manage associated risks effectively.
Cold Extraction of Phyllanthus Niruri, Chromolaena Oodorata, Melastoma Malabathricum & Azadirachta Indica Via High-Pressure Processing (HPP): Evaluation of Physiochemical Properties and Antioxidant Activity
Phyllanthus niruri, Chromolaena odorata, Melastoma malabathricum, and Azadirachta indica are among the many medicinal plants found worldwide. These plants have been widely used for medicinal purposes due to their rich bioactive compounds. Traditional extraction methods, such as boiling at high temperatures, can lead to the degradation of certain bioactive compounds, including phenolic compounds, which contribute to antioxidant activity. This degradation occurs due to heat-induced denaturation. As an alternative, High-Pressure Processing (HPP) was employed to minimize quality deterioration during extraction. HPP was conducted at two different pressures (200 MPa and 600 MPa) with three holding times (5, 10, and 15 minutes). For comparison, a traditional extraction method was also performed by boiling the samples at 100°C for 30 minutes. The extracts were analyzed for their physicochemical properties (pH and color), antioxidant activity, and total phenolic content (TPC). Antioxidant activity was assessed using the DPPH radical scavenging method, while TPC was determined using the Folin-Ciocalteu reagent. Among the tested samples, HPP-treated A. indica extract exhibited the highest antioxidant activity at 600 MPa for 10 minutes, achieving 88.55 ± 0.04% scavenging activity. The highest TPC was observed in HPP-treated A. indica at 200 MPa for 5 minutes. Based on the results, the optimal HPP parameters for maximizing antioxidant activity were found to be 600 MPa with a 10-minute holding time. In conclusion, HPP demonstrates significant potential as an effective extraction method for medicinal plant materials, offering a promising alternative to traditional heat-based extraction techniques. This study is novel in its comparative evaluation of multiple medicinal plant species under varying HPP conditions, providing new insights into parameter optimization for maximizing antioxidant yield.
Seasonal Impact of Water Parameters Variation on Signal Propagation in Underwater Communication Systems
The study explores how environmental variations affect signal propagation in freshwater bodies, focusing on five key sites: Niger River, Asejire Dam, Ede Dam, Osun River, and Eti-Osa River. Employing laboratory-based quantitative analysis, parameters such as temperature, salinity, pH, turbidity, and total dissolved solids (TDS) were measured using standard instruments. Distinct seasonal trends emerged—temperature increased by an average of 8°C in the dry season, while turbidity and TDS rose notably during the rainy period, ranging from 30–150 NTU and 25–80 mg/L in the dry season to 41–200 NTU and 30–120 mg/L in the rainy season. These variations directly influenced acoustic signal performance. The data revealed that higher temperatures improve signal velocity and reduce attenuation, whereas increased turbidity, TDS, and salinity contribute to greater scattering and absorption losses. The novelty of this work lies in its integrated assessment of multi-parameter water quality influences on underwater signal transmission, emphasizing the dual-season comparative approach within tropical freshwater systems. Unlike prior studies that generalized oceanic models, this research contextualizes findings within inland aquatic environments relevant to Nigeria. The study contributes to the existing body of knowledge by quantitatively linking environmental conditions with communication efficiency, establishing that signal reliability in Underwater Communication Systems (UWCS) is seasonally dependent. In conclusion, the results underscore the necessity of adaptive communication models that account for local hydrological dynamics to minimize signal degradation and optimize transmission efficiency across varying aquatic conditions.
A New Modified Fifth-Order Implicit Block Method for Solving Stiff and Oscillatory Problems
A new fifth-order modified implicit 3-point super class of block backward differentiation formula for solving oscillatory problems and systems of stiff ordinary differential equations (ODEs) is developed. The method is order five. The stability and convergence properties of the method demonstrate that the method is consistent, zero-stable and almost A-stable which are necessary and sufficient conditions to integrate the stiff systems and oscillatory ODEs. Numerical experiments reveal that the proposed method delivers superior performance compared to existing conventional 3-point Block Backward Differentiation Formula (3BBDF) and 3-point Super Class of Block Backward Differentiation Formula (3SBBDF) methods, making it a robust and efficient tool for addressing stiff problems.
Eco-friendly Pest Control using Organic Materials: Cinnamomum Verum, Garlic and Chili
The widespread use of chemical pesticides in agriculture poses environmental risks and health concerns prompting the development of green alternatives from natural sources. This study aims to synthesize a natural pesticide using a mixture of Cinnamomum Verum (cinnamon) essential oil, garlic and chili and characterize the functional group of the formulation. The pesticide was prepared by extracting Cinnamomum Verum essential oil through distillation and creating garlic and chili solutions by grinding the ingredients with distilled water. The formulation consisted of 25% Cinnamomum Verum essential oil (50 mL) mixed with 75% garlic and chili solution (150 mL) in a 1:3 ratio. Active components including eugenol from Cinnamomum Verum, capsaicin from chili and allicin from garlic were identified through FTIR analysis confirming potential as natural repellents. The formulated pesticide demonstrates promising pest-repellent properties by effectively reducing pest infestation and leaf damage on chili plants during field evaluations. The synergistic combination of these plant-based bioactive compounds offers a potent, eco-friendly solution for pest control thus contribute to sustainable agricultural practices and safeguarding ecological health.
Chemical Fingerprinting of Various Tea and Coffee Types Using SEM, UV-Visible and FTIR Spectroscopy
Chemical fingerprinting provides a robust approach for characterizing and differentiating various types of tea and coffee based on their unique chemical profiles. In this study, Scanning Electron Microscopy (SEM), UV-Visible (UV-Vis) and Fourier Transform Infrared (FTIR) Spectroscopy were employed to analyze and compare chemical fingerprint various types of tea and coffee samples. The study analyzed green tea, black tea, chamomile tea and coffee samples due to their distinct composition and sources of natural antioxidant properties. SEM results showed the surface morphology for all samples is varied indicating the differences in the nature of raw material, processing, composition and surface characteristics of samples. UV-Vis spectroscopy revealed distinct patterns of chromophores observed in the UV region 250-300 nm associated with key compounds such as phenolic substances, flavonoids, methylxanthine compounds and caffeine. Additionally, FTIR spectroscopy demonstrated the fingerprint spectra and functional groups for all samples such as N-H stretching, O-H stretching, C=C aromatic ring and C-O stretching vibrations revealing compositional variations such as polysaccharides, polyphenols, sugars, caffeine, fatty acids and amino acids. The results recorded clear distinctions among various tea and coffee types. This study highlights the potential of combining SEM, UV-Vis and FTIR spectroscopy as a non-destructive, cost-effective, and comprehensive toolkit for the chemical profiling of various foods, offering valuable insights for quality assessment, authentication, and adulteration detection in the food industry.
An Improved Extended 2-Point Super Class of Block Backward Differentiation Formula for Solving Stiff Initial Value Problems
A novel, enhanced two-point block backward differentiation formula has been devised for solving stiff initial value problems of ordinary differential equations, boasting superior stability properties, including zero-stability and near A-stability. Comparative analysis reveals its exceptional accuracy and efficiency, outperforming some existing methods, thereby positioning it as a viable alternative solver for addressing stiff initial value problems.
super class of block backward differentiation formula
Characterization of The Properties of South Lampung Clay as Lightweight Expanded Clay Aggregate
Bloating properties are essential to determine clay's ability to expand and form pore structures for lightweight expanded clay (LECA) applications. South Lampung clay was taken from four different places: TN, TB1, TB2, and TJ. The clay was dried at 110oC until the water content was 7%, then ground using a ball mill to 200 mesh. The clay was formed into balls with a diameter of 10 mm and then heated at 1,050oC for 15 minutes. The chemical composition was analyzed by X-ray fluorescence. X-ray diffraction was used to analyze the crystal structure formed. Topography was analyzed using FESEM. The bloating coefficient (Cb) was calculated by comparing the volume before and after heating. Based on SiO2, TN and TB1 meet the self-bloating standard with 52.28 and 56.82% content, respectively. However, based on Al2O3, only TB1 meets the minimum standard with a value of 17.46%. Based on the total flux being below 10%, all clay has the potential for self-bloating. The type of clay is kaolinite with feldspar and kaolin phases. The bloated clay was found in TB1 and TJ with values ​​of 1.08 and 1.46. Additives are needed to increase an expansion. This study can be developed to obtain the composition of local clay, which can be applied to various fields.
I-V Characteristics of GaAs/AlAs Asymmetric Spacer Layer Tunnel Diode (ASPAT) Using Statistical Validation
The Asymmetric Spacer Layer Tunnel Diode (ASPAT) has been physically fabricated and simulated using (2) Silvaco Atlas, a widely used semiconductor device simulation software. The ASPAT features an asymmetrical structure, leading to asymmetric current-voltage (I-V) characteristics, making it suitable as a zero-bias detector with low power consumption for high-frequency applications. Accurately validating these characteristics is critical to assessing the device’s performance. However, existing numerical models rely on the Poisson, Schrödinger, and Tsu-Esaki equations, which only account for tunnelling behaviour in discrete regions emitter, barrier, and collector without fully incorporating the effects of doping concentration, material composition, and interface defects. The Transfer Matrix Method (TMM), while addressing some limitations, assumes perfect interfaces, which may not always be the case in three-dimensional (3D) fabricated devices. This study aims to investigate the numerical models used for ASPAT diode design, identify their limitations, propose an improved numerical model, and validate the proposed model against existing methods. The fabrication process of the ASPAT diode involves molecular beam epitaxy (MBE) for the Gallium Arsenide/Aluminum Arsenide (GaAs/AlAs) structure, followed by metal contact deposition, with detailed consideration of doping concentrations and potential material mismatches at the interfaces. Statistical validation of experimental and simulated I-V characteristics is conducted using linear regression, non-linear regression, and hypothesis testing of slope and intercept coefficients. (1) To ensure accuracy, a 5% significance level is assumed for validation. Results indicate that the experimental and simulation data align within a justified 5% error margin, confirming ≥ 95% validation accuracy to confirm the perfect validation despite of several limitations in physical simulation. However, the impact of 3D structural effects, boundary defects, and thermal influences must be further examined to enhance ASPAT performance. This study provides a refined numerical approach to improving ASPAT diode characterization for optimized design and performance evaluation.
Sustainable Paper Production Using Treated Pineapple Leaf Fiber and Wastepaper Composites
Fibers extracted from plants offer alternatives to commercial materials to produce paper which are increasingly valuable in sustainable product development. This study investigates the potential of pineapple leaf fibers (PALF) as an alternative to synthetic fibers in composite with wastepaper for recycle paper fabrication to reduce the agricultural waste. The study focuses on the extraction and characterization by emphasizing the effects of alkaline treatment using sodium hydroxide (NaOH) on the physical and mechanical properties of the PALF. Wastepaper was then combined with treated PALF in varying ratios i.e. 1:1, 1:2, and 2:1 to create the composite paper. The properties of the synthesized PALF were evaluated in term of moisture content and tensile strength. While the morphological characteristics was evaluated using Scanning Electron Microscopy (SEM) and functional group determination by Fourier Transform Infrared Spectroscopy (FTIR). Results indicate that NaOH treatment significantly enhances the mechanical properties of PALF by improving fiber strength and reducing moisture content with the 1:2 ratio demonstrating the highest tensile strength (9234.596 Pa). Compared to the 1:1 ratio which exhibited a tensile strength of 6946.375 Pa, the 1:2 ratio resulted in a 32.9% increase in tensile strength. Similarly, when compared to the 2:1 ratio (5311.917 Pa), the 1:2 ratio showed an impressive 73.9% enhancement in tensile strength. These findings suggest that increasing the proportion of wastepaper relative to pineapple leaf fiber (PALF) enhances fiber bonding and mechanical strength, likely due to better fiber interlocking and reinforcement. With its high tensile strength and improved durability, this composite paper can be utilized in packaging materials, stationery and biodegradable wrapping papers. This study highlights the viability of PALF in the development of eco-friendly composite materials, contributing to waste reduction and promoting the use of renewable resources in material science.
Molecular Phylogenetics of Dominant Endophytic Fungi in Leaves of Vitellaria paradoxa using Internal Transcribed Spacer gene region
On a global scale, diverse fungal species live inside plant tissues in mutualistic association either as highly specific to single hosts or widespread in many species. Despite the huge importance of Vitellaria paradoxa (Shea Butter Tree) in Africa, the fungal endophytes associated with this plant have not been documented. In this study, we characterized and determined the phylogenetic relationship of the endophytic fungi in V. paradoxa. Fungal isolation was done from V. paradoxa between July and December, 2019 by cutting, sterilizing and inoculating the healthy leaves on Potato Dextrose Agar (PDA) and Water Agar (WA) for 7 and 21 days respectively. Result of the isolation showed a dominant fungal endophyte repeatedly isolated from the leaves of V. paradoxa. Morphological features of the isolates were described and the genomic DNA was extracted for molecular analyses. Accurate molecular phylogenetic analyses of the sequences of the Internal Transcribed Spacer (ITS) gene regions using maximum likelihood analysis revealed the isolate as Lasiodiplodia theobromae. This study therefore succinctly represents the first report of L. theobromae as an endophyte in leaves of V. paradoxa using a robust analysis of its phylogeny. The implication of the occurrence of this endophytic fungus from shea butter fruit is also discussed.
Assessing Water Quality in the Kelantan River Basin Using WQI: Suspended Solids and Ecosystem Health
Water quality in the Kelantan River Basin was assessed in this study using the Water Quality Index (WQI). The Department of Environment Malaysia provided secondary data for this study with seven sampling locations along the Kelantan River Basin. WQI consists of parameters Dissolved Oxygen (DO), Biological Oxygen Demand (BOD), Chemical Oxidant Demand (COD), Ammonia Nitrogen (NH3-N), Suspended Solids (SS) and pH. For each sampling station, other WQI parameters did not exceed the threshold value except SS with a medium value of 235.50 mg/L. Krukal Walis test showed that these parameters were found to be significantly different (ρ < 0.05) between sampling station locations. Based on calculation, the SS sub-index value show 16.7% were classified as clean, 2.4% as slightly polluted and 81.0% as polluted for the entire study period. WQI SS sub-index recorded 46 which are in the Polluted category. Suspended solids are the result of several processes, including river runoff and dredging. Clay is among the inorganic and organic materials that make up it. Excessive levels can bind nutrients and heavy metals, increase water temperature, and degrade water quality. The health of the river basin ecosystem was in Class II water quality determined by the average WQI of 84 at all stations. This study concluded that extensive land development activities in the surrounding areas are affecting water quality, thereby affecting the health of the Kelantan River Basin ecosystem in relation to suspended solids.
Conversion of Jatropha Curcas Oil to Biodiesel in One-Step Transesterification Using Cowbone Derived CaO/Al2O3 with Fe2(SO4)3 Catalyst
Mixture of Ferric sulphate (Fe2(SO4)3) and Calcium oxide (CaO) supported with alumina were employed as catalysts in this study. Production of biodiesel from edible sources is a threat to food security globally, to alleviate this problem biodiesel can be produced through the exploration of non-edible oils as raw materials and the use of waste resources. This work contributes to the development of a catalyst from waste cow bone supported with alumina for single step transesterication of jatropha curcas oil. The optmal conditions were observed at catalyst loading of 5 wt %, methanol to oil mole ratio of 15:1, reaction temperature of 60 oC and reaction time of 2 hours. Fe2(SO4)3 to CaO/Al2O3 ratio of 4:1 gave optimum conversion as indicated by Gas chromatography-mass spectrometry (GCMS) of fatty acid methyl ester (FAME) of 96.72% using cowbone derived CaO and 97.01% using the commercial CaO at optimum conditions. Fourier Transformed Infrared Spectroscopy (FT-IR) analysis showed important peaks in 1750 – 1730 cm-1 that confirm the presence of biodiesel. From the fuel characteristics of jatropha curcas oil methyl esters were found to be well within the range recommended by ASTM D6751 for biodiesel. Therefore, the waste-bone catalysts produced for transesterification of jatropha curcas oil successfully produced biodiesel from jatropha curcas oil using one-step simultaneous esterification and transesterification with ferric sulphate to CaO/Al2O3. The study's results suggest that non-edible jatropha curcas oil could be a good substitute for petro-diesel. Brunauer−Emmett−Teller (BET) surface area of CaO/Al2O3 was found to be 533.9 m2/g with pore volume of 0.2722 cc/g and width of 2.647nm while that of CaO was found to be 427. 5 m2/g.
Materials Engineering and Renewable energy
Mathematical Modelling of Bödewadt Flow in Nanofluid: Implications of Velocity Slip and Thermal Slip Over a Stretching Disk
This paper investigates the flow and heat transfer attributes of Bödewadt flow in nanofluid, accounting for velocity slip, thermal slip, and a radially stretching permeable disk. The von Kármán similarity variables have been applied to simplify the governing partial differential equations into nonlinear ordinary differential equations, which are subsequently solved numerically using Python’s solve_bvp module. The results indicate that an adequate amount of stretching rate is required for the heat transfer equation's similarity solution to be present in the case of a no-slip stretching disk in order to satisfy the boundary conditions. The momentum and thermal boundary layer thickness are affected by the presence of velocity slip and thermal slip, along with stretching parameter. Additionally, variation of the local skin friction coefficient and local Nusselt number shows that heat transfer enhancement occurs in optimal situations when the slip value is minimal, a higher volume fraction of nanoparticles is used, and larger stretching parameters are applied.
Applied Mathematics in Fluid Mechanics and Heat Transfer
Copyright (c) 2024 Journal of Science and Technology
Stability Evaluation of Zinc Oxide Nanofluids Using Mangifera Odorata Extracted Peels and Leaves
The most widely utilized materials to produce nanofluids (NFs) are metal oxides, which have limitations regarding dispersion stability. Producing stable NFs is a crucial step in enhancing their functionality in real-world applications. This study aims to determine the ideal conditions for NFs utilizing a more ecologically friendly technique by synthesizing zinc oxide (ZnO) NFs using Mangifera Odorata (MO) peel and leaves extract. The stability of NFs was assessed using an optical photograph, an ultraviolet (UV) – visible spectrophotometer, and a Fourier Transform Infrared Spectrophotometer (FTIR) under different conditions, including varying extracted MO to ZnO ratios and extracted MO pH. The results show that Zinc Oxide-Mangifera Odorata peel (ZnO–MOp) and Zinc Oxide–Mangifera Odorata leaves (ZnO–MOl) NFs at pH 8 and MO extract to ZnO ratios of 1:9 indicate the most stable NFs due to the low separation rate sedimentation over 18 and 24 hours of observation. Furthermore, it was discovered that the existence of Zn–O stretching functional groups was demonstrated by the strong peaks in the 585–590 cm−1 spectrum. These findings would eventually serve as a benchmark for future study, resulting in more stable and high-quality ZnO–MO NFs for use in wastewater treatment.
Microstructure and Mechanical Characteristics of Welded AISI 1020 Low Carbon Steel Based on the Influence of Weld Joint Design and Shielded Metal Arc Welding Process
This study examines the impact of joint design on the microstructure and mechanical properties of welded AISI 1020 low carbon steel using Shielded Metal Arc Welding (SMAW) with E6013 electrodes. Bevel, butt, and half-lap joints were welded under identical conditions and assessed for mechanical and microstructural performance. The bevel joint exhibited the best overall performance, with improved tensile strength (188.39 MPa), yield strength (113.98 MPa), and impact strength (34.54 J/mm²) compared to butt and half-lap joints due to better weld penetration and load distribution. Microstructural analysis using optical microscope confirmed the presence of distinct ferrite morphologies, including ferrite, Widmanstätten ferrite, and acicular ferrite in the weld metal. The uniform distribution of phases and minimal welding defects in the weld metal zones of the bevel joint further support its mechanical superiority. These results highlight the importance of joint design in optimizing welded steel structures, with the bevel joint proving most suitable for high-strength applications. Hence, the research contributes to the understanding of the effects of joint geometry on welded steel properties and provides practical insights for industrial welding applications.
Morphology and Physiochemical Characterization of Perfluorosulfonic Acid (PFSA) Membrane for Electrochemical Application
This report provides a thorough examination of the surface morphology, chemical content, and physical properties of Perfluorosulfonic Acid (PFSA) membrane which is commonly utilised as a conductive membrane in fuel cells, ionic batteries, and electrolysers. This experimental effort is separated into two parts: morphological characterisation and physicochemical analysis, which aim to improve understanding of the membrane functional qualities. The membrane surface and cross-sectional characteristics were examined at varied magnifications using Field Emission Scanning Electron Microscopy (FESEM) and Energy-Dispersive X-ray Spectroscopy (EDX). The EDX results revealed that the membrane surface is predominantly composed of carbon (C), oxygen (O), manganese (Mn), and nickel (Ni), accounting for 22.82% by mass, whereas the cross-section analysis revealed higher mass percentages of titanium (Ti), sulphur (S), oxygen (O), carbon (C), and fluorine (F), totalling 53.51%. Tensile testing confirmed the membrane's strength, with a tensile stress of 13.71 N/mm² and an elongation at break of 73.73%. Thermal stability and breakdown behaviour were determined using Thermogravimetric Analysis (TGA), which validated this membrane thermal endurance at 422oC degradation temperatures. These findings provide significant understanding into the surface morphology and structural functional features of PFSA membrane which allow its optimisation for advanced electrochemical applications.
Evaluation of a Mechanistic Model and Finite Element Analysis for Geosynthetic-Reinforced Sub-grade Material Performance Under Cyclic Loading
This study investigates the outcomes of triaxial repeated loading tests on geosynthetic reinforced base course materials intended for road construction. Triaxial testing was utilized to simulate the impact of traffic loads. Two types of samples were examined: one set without reinforcement and another with reinforcement. The research included a thorough series of tests that varied parameters such as density, moisture content, initial effective stress, and cyclic loading conditions. The findings can be illustrated through deformation and failure envelopes applicable to various cycle counts. Factors such as the material's compaction level, moisture content, and saturation degree significantly affect its deformability. An elastic-plastic analysis utilizing the finite element method (FEM) was conducted to validate the experimental results and to establish the parameters necessary for the FEM analysis of the pavement. Utilizing the principles outlined in the AASHTO pavement design methodology, the necessary combined load-bearing capacity of the pavement layers situated above the sub-grade was determined. Additionally, the AASHTO geosynthetic reinforced roadway design approach was established. The mechanical properties, specifically strength and stiffness of reinforced with geosynthetics at various elevations were assessed through both static and cyclic triaxial testing methods. It was noted that the positive impacts of reinforcement were closely linked to the amount of reinforcement used, with the advantages of geosynthetic reinforcement becoming particularly apparent at higher strain levels.
Civil Engineering / Geotechnical & Geoenvironmental Engineering
Water Quality and Plankton Assemblages in Eniong Creek: Implications for Biodiversity and Anthropogenic Influence
The water quality and plankton assemblages of Eniong Creek were studied between August 2022 and January 2023 in three sampling points. Plankton and water samples were collected monthly using plankton net and water sampler. The water and plankton samples were analyzed using standard laboratory techniques. The results showed that some values of pH, PO-4, BOD5 and all TSS, and DO did not conform to the acceptable limits. A total of 33 species of phytoplankton from three taxonomic classes were recorded: dominated by Baccillariophyceae with 17 species and 401 individuals (59.8%). A total of 26 zooplankton species from four taxonomic classes were recorded. Monogononta (Rotifar) was the most dominant and abundant class with 12 species and 357 individuals (47.1%). Melosira granulata was the most abundant phytoplankton species (36, 5.4%), while Lecane bulla was the most abundant zooplankton species (62, 8.2%). The biodiversity- Margalef’s index: 4.769-4.963 (Phytoplankton) and 3.711- 4.109 (Zooplankton), Shannon-Weiner index: 3.075 (Phytoplankton) and 2.85-2.99 (Zooplankton), and Pielou Evenness index: 0.802-0.874 (phytoplankton) and 0.799-0.842 (Zooplankton) suggest moderate. It can be concluded that the composition, abundance and distribution of plankton in was influenced by the physicochemical conditions of the Creek, which in turn was influenced by human activities.
Modelling and Forecasting of Crude Oil Price Return Volatility from 2006-2023: An Application of the Garch Models
The volatility dynamics of Nigerian crude oil prices from 2006 to 2023 were investigated in this work using the generalized autoregressive conditional heteroskedasticity (GARCH) modeling technique. Strong evidence of time-varying conditional heteroskedasticity in the dataset was found using diagnostic tests. The model information criteria showed that the dependencies were well represented by the parsimonious GARCH (1,1) formulation. Based on maximum log-likelihood and information criterion values, exponential GARCH (EGARCH) showed the best in-sample fit. The projection predicts prices beginning at a very high level in 2024 and then rapidly falling, with a steep downward slope in the expected price trajectory. The model predicts that by the end of 2025, crude oil prices will be significantly lower than they were at the start of the projection period. Overall, our empirical findings give good support for using EGARCH techniques to forecast volatility in Nigerian crude oil returns. As a result, practitioners now have access to efficient prediction tools that have been verified using rigorous statistical approaches to help them estimate future price risk.
Identification of Flavonoid Content in Cucumis Sativus L. Peels with Dissimilar Polarity Solvents
The study aimed to quantify flavonoid content in two types of Cucumis Sativus L. peels (regular and Japanese variants) using solvents with different polarities. The solvents utilized were water, 50% ethanol and 50% acetone which the yield was compared, and the flavonoid was extracted. The Shinoda test was employed to qualitatively determine the presence of flavonoids, indicated by changes to pale pink colour and colour disappearance upon the addition of HCl and magnesium ribbon. Quantitative analysis was performed using the aluminum chloride colorimetric method. Japanese cucumber peel extracted with 50% ethanol had the highest total flavonoid content (TFC) of 2.20 mg QE/g, while regular cucumber peel extracted with 50% ethanol had a total flavonoid content (TFC) of 1.20 mg QE/g. The study indicated that solvent polarity significantly influences flavonoid extraction, with ethanol being more effective for Japanese cucumber variants.