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Research Article
Green Synthesis, Characterization, and Antimicrobial Activity of ZnO Nanoparticles Using Zanthoxylum gilletii Leaf Extract
Issue:
Volume 11, Issue 3, September 2026
Pages:
92-103
Received:
16 June 2026
Accepted:
26 June 2026
Published:
17 July 2026
Abstract: The green synthesis of zinc oxide (ZnO) nanoparticles has attracted significant attention as an eco-friendly alternative to conventional chemical methods. In this study, ZnO nanoparticles were synthesized using aqueous leaf extract of Zanthoxylum gilletii, where plant phytochemicals acted as reducing and stabilizing agents. Key synthesis parameters, including precursor concentration, reaction pH, and temperature, were systematically optimized to obtain nanoparticles with desirable physicochemical properties. Optimal synthesis conditions were achieved at 0.7 M precursor concentration, pH 10, and 60°C, resulting in well-defined and stable nanoparticles. The synthesized ZnO nanoparticles were characterized using UV–Visible spectroscopy, Fourier Transform Infrared (FTIR) spectroscopy, X-ray diffraction (XRD), and photoluminescence (PL) analysis. UV–Vis results showed a characteristic absorption peak at 356 nm with a band gap of 3.12 eV, confirming ZnO formation. FTIR analysis revealed a Zn–O stretching vibration at ~410 cm-1, while XRD confirmed a hexagonal wurtzite structure with an average crystallite size of 29.70 nm. PL spectra exhibited an emission peak at 401 nm, indicating defect-related optical behaviour. The antimicrobial activity of the synthesized nanoparticles was evaluated against Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, and Candida albicans using the agar disc diffusion method. The nanoparticles exhibited significant antimicrobial activity, with mean zones of inhibition ranging from 18.67 mm to 22.00 mm. Statistical analysis (one-way ANOVA, p > 0.05) indicated no significant difference among the tested microorganisms, demonstrating consistent broad-spectrum antimicrobial performance. These findings demonstrate that Zanthoxylum gilletii-mediated green synthesis provides an effective and sustainable approach for producing ZnO nanoparticles with controlled structural and optical properties and strong antimicrobial potential.
Abstract: The green synthesis of zinc oxide (ZnO) nanoparticles has attracted significant attention as an eco-friendly alternative to conventional chemical methods. In this study, ZnO nanoparticles were synthesized using aqueous leaf extract of Zanthoxylum gilletii, where plant phytochemicals acted as reducing and stabilizing agents. Key synthesis parameters...
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Research Article
The Effect of Food Quality, Price, and Menu Variety on Consumer Repurchase in Restaurant
Issue:
Volume 11, Issue 3, September 2026
Pages:
104-114
Received:
7 June 2026
Accepted:
27 June 2026
Published:
22 July 2026
Abstract: Repurchase intention is essential for sustaining the competitiveness of hotel restaurants because repeat guests contribute to long-term profitability and customer loyalty. Although previous studies have examined the effects of food quality, price, and menu variety on customer behaviour, limited research has simultaneously investigated their relationships with repurchase intention through the mediating role of guest satisfaction in the context of hotel restaurants. Therefore, this study aims to examine the direct and indirect effects of food quality, price, and menu variety on repurchase intention, with guest satisfaction serving as a mediating variable. A quantitative causal research design was employed using a survey of 220 guests who had dined at Tjokro Restaurant, Grand Tjokro Hotel Yogyakarta. Data were collected through a structured questionnaire and analyzed using Partial Least Squares Structural Equation Modelling (PLS-SEM). The findings reveal that food quality and menu variety have positive and significant effects on both guest satisfaction and repurchase intention. Price has a significant negative effect on guest satisfaction but does not directly influence repurchase intention. Guest satisfaction positively affects repurchase intention and significantly mediates the relationships between food quality, price, menu variety, and repurchase intention. These findings demonstrate that repeat-purchase behaviour in hotel restaurants is driven not only by product-related attributes but also by guests' overall satisfaction with their dining experience. The study contributes to hospitality marketing literature by clarifying the mediating role of guest satisfaction and provides practical guidance for hotel managers in designing effective menu, pricing, and food quality strategies to encourage repeat patronage.
Abstract: Repurchase intention is essential for sustaining the competitiveness of hotel restaurants because repeat guests contribute to long-term profitability and customer loyalty. Although previous studies have examined the effects of food quality, price, and menu variety on customer behaviour, limited research has simultaneously investigated their relatio...
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Research Article
Economic Performance Analysis of Organic Rankine Cycle Retrofit for Carbon Neutral Shipping in the Gulf of Guinea
Victor Effiong Odokowo*
,
Robert Poku,
Oyinkepreye Lucky Bebeteidoh,
Ezenwa Alfred Ogbonnaya
Issue:
Volume 11, Issue 3, September 2026
Pages:
115-129
Received:
10 June 2026
Accepted:
8 July 2026
Published:
28 July 2026
Abstract: This study presents a detailed economic assessment tailored for retrofitting marine diesel engine (MDE) with Organic Rankine Cycle (ORC) towards attaining energy efficiency and carbon neutrality in shipping. Addressing a vital gap in current research, the study, adeptly synchronizes thermodynamics, mass and energy balance equations coupled with economic indices to assess the viability of ORC retrofit technology onboard a tanker vessel on voyage in the Gulf of Guinea (GoG). To define a roadmap to the adoption of ORC onboard towards economic, energy and emission efficiency, the simulation and analysis were brought to fruition applying MATLAB. The results obtained establish that employing ORC retrofit significantly boosts the overall ship operational and economic performances by converting Waste Heat (WH) into power. Results showed that ORC retrofit remains attractive in the case study ship, with a Capital Expenditure (CAPEX) range of 20 to 60%, providing a lower Levelized Cost of Electricity (LCOE) and maximum Net Present Value (NPV). An interest rate of less than 8 % produces a strongly positive NPV and a LCOE of ₦80 per kWh. A rise in fuel price to about 0.9% cost/kg has a positive effect on the IRR and a reduction in the DPBT below 4 years. Analysis revealed that below 60% of base running hours, the NPV may turn negative causing the ORC retrofit investment unbeneficial and unviable. Above 60% of base running hours, the NPV rises, signaling the ranges of viability of the ORC retrofit especially in the GOG. The study also highlights the importance of adopting a well-matched ORC unit based on a vessel’s peculiarity of WH. Also, a proper blend of economic indicators is imperative to achieve an economically viable retrofitted system for enhanced operational and energy efficiency for a carbon neutral shipping.
Abstract: This study presents a detailed economic assessment tailored for retrofitting marine diesel engine (MDE) with Organic Rankine Cycle (ORC) towards attaining energy efficiency and carbon neutrality in shipping. Addressing a vital gap in current research, the study, adeptly synchronizes thermodynamics, mass and energy balance equations coupled with eco...
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Review Article
A Review on Corrosion Mitigation Strategies for Reinforced Concrete Structures Exposed to Climate Events
Mostafa Hassan*
Issue:
Volume 11, Issue 3, September 2026
Pages:
130-148
Received:
14 July 2026
Accepted:
23 July 2026
Published:
17 August 2026
Abstract: The propagation of deterioration in vital reinforced concrete (RC) structures is a critical issue for infrastructure subjected to extreme climate change. Billions of US dollars were spent annually on the rehabilitation of RC structures. Accurate projections of future climate data for each city worldwide must consider their influence on RC members. This research will present a review of some existing RC structures exposed to CO2 and chloride-induced corrosion. Moreover, this research will discuss methods for investigating the projection of extreme climate events, providing a framework for projecting future climate data. The limit state functions for carbonation and chloride-induced corrosion are provided for various concrete sections and crack widths to predict the reliability index for assessing structural safety. This study will discuss sustainable materials and corrosion mitigation strategies to inhibit chloride- and carbonation-induced corrosion. It was deduced that a geopolymer concrete (GPC) material composed of 40% fly ash (FA) and 60% slag (SG) shows good resistance to chloride-induced corrosion compared to an ordinary Portland cement concrete mix and a GPC mix composed of 50% FA and 50% SG. Furthermore, GPC, which consists of 40% FA and 60% SG, will increase the service life of the RC structure compared to a mix composed of 50% FA and 50% SG. Finally, a crack width limitation for RC structures located in different climate regions must be assessed in various codes to adapt them to the future projection of extreme climates to reduce the risks to RC structures.
Abstract: The propagation of deterioration in vital reinforced concrete (RC) structures is a critical issue for infrastructure subjected to extreme climate change. Billions of US dollars were spent annually on the rehabilitation of RC structures. Accurate projections of future climate data for each city worldwide must consider their influence on RC members. ...
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Research Article
An Efficient Tropical Cyclone Center Prediction Scheme Using Firefly Algorithm in Infrared Image (IR)
Douglas Omwenga Nyabuga*
Issue:
Volume 11, Issue 3, September 2026
Pages:
149-158
Received:
8 July 2026
Accepted:
22 July 2026
Published:
18 August 2026
Abstract: Tropical cyclones have a strong potential to bring significant economic loss to cyclone-prone areas. Locating the tropical cyclone center is significant and necessary for the timely forecasting of tropical cyclones. The observation of the typhoon's center, primarily carried out through the use of infrared (IR) images, is not easy. In some situations, the typhoon center is identified by the typhoon eye, which is overlaid on an infrared image. Therefore, the purpose of this study is to address the challenges of tropical cyclone center localization in infrared images by developing a firefly algorithm-based optimization scheme for accurate center prediction. This research proposes an efficient tropical cyclone center prediction scheme with optimization performed by the firefly algorithm to predict the central point in tropical cyclone infrared images. In addition, problems associated with pattern matching and other localization challenges are addressed through the optimization process to obtain the most accurate tropical cyclone center. Finally, the proposed scheme achieved highly accurate center localization. The proposed approach contributes to the scientific community by providing an optimization-based framework for tropical cyclone center localization that can support future research in automated cyclone analysis, infrared satellite image processing, and the development of more reliable tropical cyclone forecasting methods.
Abstract: Tropical cyclones have a strong potential to bring significant economic loss to cyclone-prone areas. Locating the tropical cyclone center is significant and necessary for the timely forecasting of tropical cyclones. The observation of the typhoon's center, primarily carried out through the use of infrared (IR) images, is not easy. In some situation...
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Research Article
Design, Development, and Structural Validation of a Mobile Static Test Stand for Solid Rocket Motor Performance Evaluation
Issue:
Volume 11, Issue 3, September 2026
Pages:
159-172
Received:
18 July 2026
Accepted:
30 July 2026
Published:
20 August 2026
Abstract: Reliable static firing facilities are indispensable for evaluating the performance, structural integrity, and operational safety of solid rocket motors (SRMs). However, the high cost and limited availability of dedicated propulsion test facilities continue to constrain experimental rocket propulsion research in many developing countries. This study presents the design, fabrication, and structural validation of a cost-effective mobile static test stand developed at the Advanced Aerospace Engines Laboratory (AAEL) in Nigeria to support indigenous solid rocket motor research and development. The developed facility integrates a rigid steel support structure, an adjustable motor mounting assembly, a centrally mounted compression load cell, a dedicated thrust data acquisition system, a programmable remote ignition controller, and a reinforced steel safety cage equipped with wireless 4K night-vision cameras for real-time remote monitoring. The ignition system incorporates a programmable 30-second countdown sequence, an audible warning alarm, wireless remote firing capability over distances up to 400 m, and an emergency abort function to enhance operational safety. The structural components of the test stand were designed using conventional mechanical design principles and validated through finite element analysis to ensure adequate stiffness and structural integrity under the maximum expected loading conditions. Real-time thrust measurements are obtained through a calibrated compression load cell integrated with a dedicated data acquisition system capable of continuously recording thrust throughout the combustion process. The developed test facility provides a practical, reliable, and economically sustainable platform for the experimental evaluation of solid rocket motors developed within Nigeria's indigenous space programme.
Abstract: Reliable static firing facilities are indispensable for evaluating the performance, structural integrity, and operational safety of solid rocket motors (SRMs). However, the high cost and limited availability of dedicated propulsion test facilities continue to constrain experimental rocket propulsion research in many developing countries. This study...
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Research Article
Evaluating Carbonation-Induced Corrosion Initiation Reliability Index for Reinforced Concrete Sections Exposed to Severe Maximum Temperature Levels
Mostafa Hassan*
Issue:
Volume 11, Issue 3, September 2026
Pages:
173-185
Received:
21 July 2026
Accepted:
3 August 2026
Published:
20 August 2026
Abstract: The purpose of this research is to evaluate the carbonation depth and the probability of carbonation-induced corrosion initiation (PCICI) values across various temperature levels for concrete mixes, including various percentages of fly ash (FA). The concrete sections are subjected to a combination of severe peak temperatures and CO2 concentrations. Moreover, the maximum temperature levels varied from 25°C to 45°C, reflecting their effects on the diffusion coefficient. The concrete cover (CV) thicknesses used in the probabilistic corrosion model range from 40 mm to 70 mm. The width of the crack (CW) variability ranges from 0.05 to 0.25 mm for cracked sections to determine their effect on probabilistic corrosion initiation. The concrete mixes include various percentages and types of FA, ranging from 5% to 30%, as supplementary cementitious materials (SCMs). The Monte Carlo simulation method is used in conducting the probabilistic corrosion model due to its accuracy. It was deduced that, for a cracked concrete section with a CV of 70 mm and a CW of 0.1 mm, PCICI is significant at 5% when low-calcium fly ash (LCFA) is utilized in the concrete mix, exposed to various severe temperature levels exceeding 30°C. Finally, the impact of using 30% LCFA as SCM poses a high risk on PCICI for uncracked CV of 45 mm, when subjected to maximum temperatures ranging from 35°C to 45°C.
Abstract: The purpose of this research is to evaluate the carbonation depth and the probability of carbonation-induced corrosion initiation (PCICI) values across various temperature levels for concrete mixes, including various percentages of fly ash (FA). The concrete sections are subjected to a combination of severe peak temperatures and CO2 concentrations....
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