Scientific African最新文献_第2页

Electrochemical determination of ascorbic acid at Ag2S - CuO - ZnO ternary nanocomposite modified glassy carbon electrode

IF 2.7

Scientific African Pub Date : 2025-03-24 DOI: 10.1016/j.sciaf.2025.e02669

Abdulwahid Abamecha, Ahmed Awol Yimer, Guta Gonfa Muleta, Shimeles Addisu Kitte

{"title":"Electrochemical determination of ascorbic acid at Ag2S - CuO - ZnO ternary nanocomposite modified glassy carbon electrode","authors":"Abdulwahid Abamecha, Ahmed Awol Yimer, Guta Gonfa Muleta, Shimeles Addisu Kitte","doi":"10.1016/j.sciaf.2025.e02669","DOIUrl":"10.1016/j.sciaf.2025.e02669","url":null,"abstract":"<div><div>In this work, a novel ternary nanocomposite electrochemical sensor based on Ag<sub>2</sub>S-CuO-ZnO was developed and put to use for ascorbic acid (AA) electrochemical detection. By combining CuO-ZnO and AgNO<sub>3</sub> precursors, an easy-to-use and inexpensive homogeneous precipitation procedure was used to produce the Ag<sub>2</sub>S-CuO-ZnO nanocomposite. X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared (FT-IR), and ultraviolet-visible (UV–VIS) spectroscopy were used to analyze the produced ternary nanocomposite. AA displayed an irreversible oxidation peak on the cyclic voltammograms (CVs) at Ag<sub>2</sub>S-CuO-ZnO nanocomposite modified glassy carbon electrode (Ag<sub>2</sub>S-CuO-ZnO/GCE). The enhanced sensitivity of AA detection at Ag<sub>2</sub>S-CuO-ZnO/GCE was attributed to the ternary nanocomposite's synergistic effects and improved electron transfer efficiency. Using linear sweep voltammetry (LSV), the proposed electrochemical sensor demonstrated a linear range of 1 - 150 μM with a limit of detection (LOD) of 0.73 μM. The demonstrated sensor's practical applicability was successfully used to determine the amount of AA in an orange sample.</div></div>","PeriodicalId":21690,"journal":{"name":"Scientific African","volume":"28 ","pages":"Article e02669"},"PeriodicalIF":2.7,"publicationDate":"2025-03-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143715177","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

QSPR analysis of vitiligo treatment of some drugs using reverse degree-based topological indices

IF 2.7

Scientific African Pub Date : 2025-03-24 DOI: 10.1016/j.sciaf.2025.e02636

S. Gayathri , K. Dhanalakshmi , Ebenezer Bonyah

引用次数: 0

Thermochemical calculations to monitor the fate of heavy metals during solid waste incineration

IF 2.7

Scientific African Pub Date : 2025-03-24 DOI: 10.1016/j.sciaf.2025.e02672

Fatima-Zahra Abbadi , Karima Azoulay , Ahmed Ait Hou , Saloua Jemjami

{"title":"Thermochemical calculations to monitor the fate of heavy metals during solid waste incineration","authors":"Fatima-Zahra Abbadi , Karima Azoulay , Ahmed Ait Hou , Saloua Jemjami","doi":"10.1016/j.sciaf.2025.e02672","DOIUrl":"10.1016/j.sciaf.2025.e02672","url":null,"abstract":"<div><div>Thermodynamic equilibrium calculations have become essential for analyzing physicochemical processes and developing innovative technologies aimed at optimizing resource utilization and mitigating environmental pollution.</div><div>Our study applies thermochemical modeling using HSC Chemistry software to examine the fate of heavy metals—copper (Cu), zinc (Zn), and lead (Pb)—during waste incineration. The objective is to assess the influence of key parameters, including temperature, chlorine content, and total pressure, on the volatilization, condensation, and retention of these metals in solid residues.</div><div>The simulations reveal that elevated temperatures predominantly favor the formation of gaseous metal species at the expense of solid-phase retention, whereas an increased chlorine content promotes the stabilization of heavy metals in solid form. Furthermore, rising total pressure is observed to enhance the fraction of solid species while simultaneously reducing the prevalence of volatile species.</div><div>These results provide a deeper understanding of the physicochemical mechanisms governing the fate of heavy metals during thermal waste treatment. The findings have direct implications for optimizing incineration protocols, refining pollution control strategies, and mitigating environmental risks associated with the atmospheric dispersion of toxic metal emissions.</div></div>","PeriodicalId":21690,"journal":{"name":"Scientific African","volume":"28 ","pages":"Article e02672"},"PeriodicalIF":2.7,"publicationDate":"2025-03-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143725396","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Thermal performance enhancement of elliptical absorbers in cylindrical-parabolic solar collectors: A CFD-Based comparative study

IF 2.7

Scientific African Pub Date : 2025-03-22 DOI: 10.1016/j.sciaf.2025.e02664

Hidayet Meroua Sefiani , Faycal Bouzit , Abderrahmane Elmeriah , Riyadh Bouddou , Ayodeji Olalekan Salau , Benali alouache , Kawther Berrahi , Mohammed El Amine Feraoun , Abdelkader Benaziza

{"title":"Thermal performance enhancement of elliptical absorbers in cylindrical-parabolic solar collectors: A CFD-Based comparative study","authors":"Hidayet Meroua Sefiani , Faycal Bouzit , Abderrahmane Elmeriah , Riyadh Bouddou , Ayodeji Olalekan Salau , Benali alouache , Kawther Berrahi , Mohammed El Amine Feraoun , Abdelkader Benaziza","doi":"10.1016/j.sciaf.2025.e02664","DOIUrl":"10.1016/j.sciaf.2025.e02664","url":null,"abstract":"<div><div>In this research paper, the computational fluid dynamics (CFD) technique was implemented for analyzing and improving the thermal efficiency of a parabolic trough collector (PTC). The effect of the elliptical absorber geometry under turbulent flow and non-uniform heat flux was investigated numerically and compared with empirical correlations to verify the proposed method. Additionally, it was noted that the elliptical absorber tube design increased the Nusselt number (Nu) by 25 %, improving convective heat transfer compared with the conventional cylindrical absorber tube. Heat transfer performance increased by an additional 15 % using an HTF with 1 % aluminum oxide nanoparticles (Al₂O₃). Integrating the elliptical geometry with the nanofluids enhanced the overall thermal efficiency by 40 %. The thermal performance evaluation criterion (PEC) exceeded 20 %, confirming the design's suitability. The elliptical configuration reduced the absorber wall temperature by 10 %, resulting in a decrease in thermal stress and a corresponding increase in durability. However, there was a small effect on the pressure drop of 4.5 %. From the velocity field, it is evident that the fluid distribution is more uniform in the elliptical tube than in the circular tube, resulting in higher convective heat transfer coefficients. These findings validated that the elliptical absorber outperforms the circular design in thermal performance. When nanofluids are used in the elliptical absorber, the thermal performance is further improved, demonstrating the possibility of great potential in improving solar energy systems as a successful approach to increasing the efficiency of energy production for sustainable results.</div></div>","PeriodicalId":21690,"journal":{"name":"Scientific African","volume":"28 ","pages":"Article e02664"},"PeriodicalIF":2.7,"publicationDate":"2025-03-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143725397","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

GIS-based landslide susceptibility mapping using Frequency ratio method: A case study from Adigrat-Mugulat mountain chains, northern Ethiopia

IF 2.7

Scientific African Pub Date : 2025-03-22 DOI: 10.1016/j.sciaf.2025.e02661

Asmelash Abay , Aklilu Mulugeta , Gebreslassie Mebrahtu

{"title":"GIS-based landslide susceptibility mapping using Frequency ratio method: A case study from Adigrat-Mugulat mountain chains, northern Ethiopia","authors":"Asmelash Abay , Aklilu Mulugeta , Gebreslassie Mebrahtu","doi":"10.1016/j.sciaf.2025.e02661","DOIUrl":"10.1016/j.sciaf.2025.e02661","url":null,"abstract":"<div><div>Landslides are common geo-hazards in the mountainous regions of Ethiopian highlands. This study aims to assess the contributions of major causative factors of landslides and produce landslide susceptibility zonation (LSZ) map of the study area using frequency ratio (FR) method. In total, 283 landslides were identified using field campaigns, aerial photos, and Google Earth. Seven causative factors, namely slope steepness, aspect, elevation, lithology, distance to drainage, land use land cover, and distance to lineament, were used for landslide susceptibility mapping. 12.7% of the study area is affected by different types of landslides. The study revealed that slope steepness, lithology, and distance to drainage have significant effect on landslide occurrences. Specifically, slope angles (>35°), distance to drainage (0 to 150 m), land use land cover (bare land), distance to lineament (0 to 400 m), and elevation (>3030 m) are prone to landslides. Moreover, slope aspects with southwest, northwest, and west orientations are more susceptible to landslides. The findings showed that 11.7% of the study area falls under low susceptibility zone, 47.68% under moderate zone, while high and very high susceptibility zones cover 30.83% and 9.79% of the area, respectively. The validation of landslide susceptibility map reveals that 84% of the inventoried landslides fall in high and very high susceptibility zones, while 14% fall in moderate zone and only 2% in low susceptibility zone. Furthermore, verification using the area under the ROC curve resulted in 87% prediction accuracy. Therefore, the generated landslide susceptibility map could serve as a baseline for future infrastructure planning and settlement.</div></div>","PeriodicalId":21690,"journal":{"name":"Scientific African","volume":"28 ","pages":"Article e02661"},"PeriodicalIF":2.7,"publicationDate":"2025-03-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143684957","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Clustering and spatial dynamics of informal trading in Zimbabwe during the COVID-19 pandemic

IF 2.7

Scientific African Pub Date : 2025-03-22 DOI: 10.1016/j.sciaf.2025.e02662

Meshach Ndlovu

引用次数: 0

Awareness and knowledge of Open Educational Resources (OERs) among postgraduate students in Ghanaian universities

IF 2.7

Scientific African Pub Date : 2025-03-22 DOI: 10.1016/j.sciaf.2025.e02659

Abudu Issah Ndaago, Philip Kwaku Kankam, Winifred Bentil

{"title":"Awareness and knowledge of Open Educational Resources (OERs) among postgraduate students in Ghanaian universities","authors":"Abudu Issah Ndaago, Philip Kwaku Kankam, Winifred Bentil","doi":"10.1016/j.sciaf.2025.e02659","DOIUrl":"10.1016/j.sciaf.2025.e02659","url":null,"abstract":"<div><div>Open Educational Resources (OERs) proficiently enhance academic resources and help promote affordable, accessible education. However, much is not known in terms of the knowledge, awareness, and sources of information about OERs among postgraduate students in Ghanaian universities. This present study examined postgraduate students' awareness, knowledge, and sources of OERs. It employed a quantitative method, using a survey study design. Data was collected with self-administered questionnaires, 344 postgraduate students responded from across the three Ghanaian universities, and analyzed using Special Package for Statistical Sciences (SPSS) version 22.0. Findings from this study revealed that OERs were generally accessible through platforms like Sakai Learning Management System, Moodle, and other institutional repositories. Although many students demonstrated some basic level of awareness, a significant proportion of the students lacked familiarity with specific OERs and their components. The university libraries were identified as dominant providers of OER materials, alongside academic advisors, conferences, and colleagues. The findings from this study also emphasize the need for targeted educational interventions, such as workshops, training programs, and promotional activities, to bridge the awareness-usage gap to foster effective and efficient OER implementation.</div></div>","PeriodicalId":21690,"journal":{"name":"Scientific African","volume":"28 ","pages":"Article e02659"},"PeriodicalIF":2.7,"publicationDate":"2025-03-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143697639","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Optimization of biodiesel production from cottonseed oil using response surface methodology and artificial neural network techniques

IF 2.7

Scientific African Pub Date : 2025-03-21 DOI: 10.1016/j.sciaf.2025.e02665

Negasa Tesfaye Tefera, Ramesh Babu Nallamothu, Getachew Alemayehu Lakew, Teshome Kumsa Kurse

{"title":"Optimization of biodiesel production from cottonseed oil using response surface methodology and artificial neural network techniques","authors":"Negasa Tesfaye Tefera, Ramesh Babu Nallamothu, Getachew Alemayehu Lakew, Teshome Kumsa Kurse","doi":"10.1016/j.sciaf.2025.e02665","DOIUrl":"10.1016/j.sciaf.2025.e02665","url":null,"abstract":"<div><div>The depletion of fossil fuels and increasing environmental concerns necessitate the development of sustainable energy alternatives. Biodiesel, derived from renewable feedstocks, is a promising solution to address these challenges. This study focuses on optimizing biodiesel production from cottonseed oil using a hybrid modelling approach that integrates response surface methodology (RSM) and artificial neural networks (ANN). Unlike conventional studies that rely on a single optimization technique, this study combines RSM with Box-Behnken design and ANN to enhance predictive accuracy and process efficiency. Biodiesel was synthesized through transesterification using methanol and KOH catalyst, with optimization based on reaction time (40, 60, and 80 min.), concentration of catalyst (0.5, 1, and 1.5 wt. %), and methanol to oil ratio (1:4, 1:6, and 1:8). The Box-Behnken design of RSM generated an experimental design matrix, while ANN featured a 3-10-1 architecture to evaluate process variables. The highest biodiesel yield of 94.66 % was achieved at catalyst concentration (1 wt. %), a reaction duration (60 min.), and a methanol to oil ratio (1:6). The RSM quadratic model achieved an R<sup>2</sup> of 0.970 and an adj-R<sup>2</sup> of 0.968. The ANN model, trained using the Levenberg-Marquardt approach, achieved a mean squared error of 4.963e-18 and an R-value of 0.9957 at epoch 3. Gas chromatography-mass spectroscopy (GC–MS) confirmed several fatty acid concentrations in the methyl ester. Furthermore, the biodiesel's key physicochemical properties meet EN 14214 and ASTM D6751 standards. This study contributes to advancing renewable energy sources by utilizing cottonseed oil, thereby promoting environmental sustainability.</div></div>","PeriodicalId":21690,"journal":{"name":"Scientific African","volume":"28 ","pages":"Article e02665"},"PeriodicalIF":2.7,"publicationDate":"2025-03-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143684946","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Development of solid phase extraction method for the LC-PDA detection of selected pharmaceuticals and their metabolites in surface water and sediment from the Isipingo River, KZN, South Africa

IF 2.7

Scientific African Pub Date : 2025-03-20 DOI: 10.1016/j.sciaf.2025.e02655

Lemien Thavarayan, Brenda Moodley

{"title":"Development of solid phase extraction method for the LC-PDA detection of selected pharmaceuticals and their metabolites in surface water and sediment from the Isipingo River, KZN, South Africa","authors":"Lemien Thavarayan, Brenda Moodley","doi":"10.1016/j.sciaf.2025.e02655","DOIUrl":"10.1016/j.sciaf.2025.e02655","url":null,"abstract":"<div><div>Multiple reports of pharmaceuticals and personal care products (PPCP's) have been established worldwide in different matrices of the environment. However, only a few of these investigations cover their metabolites in the environment. This study addresses the detection of ten selected pharmaceuticals including their dominant metabolites in surface water and sediments along the Isipingo River, KwaZulu-Natal, South Africa. A solid phase extraction method was developed for the simultaneous extraction of these targeted pharmaceuticals from different therapeutic groups in sediment and surface water samples. The extracted samples were analyzed using LC-PDA. Extraction times, solvent extraction, SPE sorbent type and extraction pH were optimized for both sediment and surface water samples to produce an overall analyte recovery of 59 -109 %. The limit of detection for surface water and sediments were 0.012–0.211 µg/L and 0.848–2.756 µg/kg, respectively. All target analytes and their dominant metabolites were detected in the range of 0.11–3.68 µg/L and 1.76–117.2 µg/kg for surface water and sediments, respectively. The trends show an increase in total PPCP levels along the flow of the river with the highest amounts detected at the outflow of the diversion works for sediments 358.89 µg/kg and surface water 11.07 ug/L.</div></div>","PeriodicalId":21690,"journal":{"name":"Scientific African","volume":"28 ","pages":"Article e02655"},"PeriodicalIF":2.7,"publicationDate":"2025-03-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143697635","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Spatio-temporal crime pattern analysis in Addis Ketema, Addis Ababa, Ethiopia: GIS and R based approaches

IF 2.7

Scientific African Pub Date : 2025-03-20 DOI: 10.1016/j.sciaf.2025.e02656

Ziyen Achamyeleh Mekonnen , Esubalew Mulugeta Engda , Kanenus Fufa Deraro , Natnael Agegnehu , Talema Moged Reda , Muralitharan Jothimani

{"title":"Spatio-temporal crime pattern analysis in Addis Ketema, Addis Ababa, Ethiopia: GIS and R based approaches","authors":"Ziyen Achamyeleh Mekonnen , Esubalew Mulugeta Engda , Kanenus Fufa Deraro , Natnael Agegnehu , Talema Moged Reda , Muralitharan Jothimani","doi":"10.1016/j.sciaf.2025.e02656","DOIUrl":"10.1016/j.sciaf.2025.e02656","url":null,"abstract":"<div><div>Spatio-temporal crime analysis is a critical component of modern law enforcement and urban planning, aiming to understand the dynamic nature of criminal activities within a geographic context. This study presents a comprehensive approach to spatio-temporal crime analysis using R programming language. The study begins by collecting and preprocessing 5-year crime data, incorporating both spatial and temporal dimensions. It applies various exploratory data analyses to unveil underlying patterns and trends in the data, including hotspot identification, density estimation, and cluster detection to pinpoint areas of high criminal activity and potential crime clusters. The results reveal that fraud, accounting for 19.5 % of reported crimes, is the most prevalent crime, followed by attempted murder (11.1 %) and drug offenses (9 %). Temporal trends indicate that fraud peaked in 2018, while attempted murders showed the highest frequency in 2021. Crime incidents were most frequent in the summer months, with notable spikes in June and July for attempted murder, and August through October for fraud. The spatial analysis identified crime hotspots in areas such as Merkato and Autobis Tera, where commercial activity and transportation hubs correlate with high crime concentrations. The study recommends continuously collecting and analyzing crime data to identify emerging trends and adapt strategies accordingly.</div></div>","PeriodicalId":21690,"journal":{"name":"Scientific African","volume":"28 ","pages":"Article e02656"},"PeriodicalIF":2.7,"publicationDate":"2025-03-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143734577","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0