Pub Date : 2026-01-30DOI: 10.1016/j.sciaf.2026.e03188
Salma Moujid , Abdelilah Kaddar , Sara Soulaimani , Mohamed El Aallaoui
{"title":"Corrigendum to “Stability analysis of a fractional order unemployment model with a non-linear job creation” [Scientific African, Volume 29 (2025), Article e02828]","authors":"Salma Moujid , Abdelilah Kaddar , Sara Soulaimani , Mohamed El Aallaoui","doi":"10.1016/j.sciaf.2026.e03188","DOIUrl":"10.1016/j.sciaf.2026.e03188","url":null,"abstract":"","PeriodicalId":21690,"journal":{"name":"Scientific African","volume":"31 ","pages":"Article e03188"},"PeriodicalIF":3.3,"publicationDate":"2026-01-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146077790","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-29DOI: 10.1016/j.sciaf.2026.e03207
Eslam Abdelhakim Seyam , Shimaa Wasfy Sadk , Ibrahim A. Fares , Rasha Abd El-Wahab Attwa
In this article, the stress–strength reliability (), where both stress and strength follow a new model called Marshall Olkin’s q extended generalized extreme value linear distribution (-) under type II progressive censoring, is investigated. The estimation is considered using both maximum likelihood estimation () and Bayesian estimation (). Since the equations are extremely complex, a metaheuristic optimization technique called the Whale Optimization Algorithm (WOA) is utilized. The is considered for both informative and non informative cases using both Linex and square error loss functions. Temperature data from Sacramento and Los Angeles counties in California are also used to demonstrate the proposed statistical methodology, showing that the model provides a better fit than both and based on lower , , and values. Time series analysis, return level, and are applied to predict future temperatures, and the results consistently indicate higher predicted temperatures in Los Angeles than in Sacramento.
{"title":"Forecasting temperature data for two counties in California using the stress–strength reliability of the MO q-GEVL distribution: A return level based approach and time series","authors":"Eslam Abdelhakim Seyam , Shimaa Wasfy Sadk , Ibrahim A. Fares , Rasha Abd El-Wahab Attwa","doi":"10.1016/j.sciaf.2026.e03207","DOIUrl":"10.1016/j.sciaf.2026.e03207","url":null,"abstract":"<div><div>In this article, the stress–strength reliability (<span><math><mrow><mi>S</mi><mi>S</mi><mi>R</mi><mo>=</mo><mi>P</mi><mrow><mo>(</mo><mi>X</mi><mo><</mo><mi>Y</mi><mo>)</mo></mrow></mrow></math></span>), where both stress <span><math><mi>X</mi></math></span> and strength <span><math><mi>Y</mi></math></span> follow a new model called Marshall Olkin’s q extended generalized extreme value linear distribution (<span><math><mi>M</mi></math></span>-<span><math><mrow><mi>q</mi><mi>GEVL</mi></mrow></math></span>) under type II progressive censoring, is investigated. The <span><math><mrow><mi>S</mi><mi>S</mi><mi>R</mi></mrow></math></span> estimation is considered using both maximum likelihood estimation (<span><math><mrow><mi>M</mi><mi>L</mi><mi>E</mi></mrow></math></span>) and Bayesian estimation (<span><math><mrow><mi>B</mi><mi>E</mi></mrow></math></span>). Since the <span><math><mrow><mi>M</mi><mi>L</mi><mi>E</mi></mrow></math></span> equations are extremely complex, a metaheuristic optimization technique called the Whale Optimization Algorithm (WOA) is utilized. The <span><math><mrow><mi>B</mi><mi>E</mi></mrow></math></span> is considered for both informative and non informative cases using both Linex and square error loss functions. Temperature data from Sacramento and Los Angeles counties in California are also used to demonstrate the proposed statistical methodology, showing that the <span><math><mrow><mi>M</mi><mtext>-</mtext><mi>q</mi><mi>G</mi><mi>E</mi><mi>V</mi><mi>L</mi></mrow></math></span> model provides a better fit than both <span><math><mrow><mi>q</mi><mi>G</mi><mi>E</mi><mi>V</mi><mi>L</mi></mrow></math></span> and <span><math><mrow><mi>G</mi><mi>E</mi><mi>V</mi><mi>L</mi></mrow></math></span> based on lower <span><math><mrow><mi>S</mi><mi>K</mi></mrow></math></span>, <span><math><mrow><mi>A</mi><mi>I</mi><mi>C</mi></mrow></math></span>, and <span><math><mrow><mi>B</mi><mi>I</mi><mi>C</mi></mrow></math></span> values. Time series analysis, return level, and <span><math><mrow><mi>S</mi><mi>S</mi><mi>R</mi></mrow></math></span> are applied to predict future temperatures, and the results consistently indicate higher predicted temperatures in Los Angeles than in Sacramento.</div></div>","PeriodicalId":21690,"journal":{"name":"Scientific African","volume":"31 ","pages":"Article e03207"},"PeriodicalIF":3.3,"publicationDate":"2026-01-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146077788","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-29DOI: 10.1016/j.sciaf.2026.e03219
Nidal Filali Baba , Ali El Myr , Youssef Bakadir , Hamed Rahmani
This paper examines the NEET phenomenon as a socioeconomic epidemic. It addresses NEET dynamics at both the population and individual levels in North Africa. We argue that NEET status is transmitted through ideational contact and propose that proximity to Europe and migration aspirations act as non-traditional factors in this transmission. The analysis draws on multiple data sources. From a cross-country perspective, we rely on the World Bank’s and SAHWA’s surveys covering 45 African countries. From an intra-country perspective, we draw on longitudinal data from the Moroccan National Employment Survey, the World Bank (2014–2022), and local administrative archives to analyze Morocco’s NEET dynamics as a representative case for North Africa.
This study makes several original contributions. First, it conceptualizes the NEET phenomenon as a socioeconomic epidemic that spreads among individuals through contact with other NEETs. Second, it adapts the Susceptible–Infected–Recovered (SIR) model to analyze NEET dynamics in Morocco. This innovative approach allows us to construct the basic reproduction number () and to identify thresholds that govern NEET trends: stagnation, extinction, and persistence. Theoretically, this approach demonstrates the relevance of epidemiological modeling in explaining how socioeconomic phenomena like NEETs spread and persist. Practically, it identifies a critical threshold for policymakers, beyond which the spread of NEETs becomes difficult to reverse.
The findings further show that proximity to major economic centers and strong migration aspirations contribute to the expansion of NEETs. This underscores the need for integrated policy responses to curb the growth of NEET populations in their origin countries and prevent their effects from spilling over into destination countries.
{"title":"NEETs phenomenon as a socioeconomic epidemic: Support for policymakers on the role of migration aspirations and proximity to economic powers","authors":"Nidal Filali Baba , Ali El Myr , Youssef Bakadir , Hamed Rahmani","doi":"10.1016/j.sciaf.2026.e03219","DOIUrl":"10.1016/j.sciaf.2026.e03219","url":null,"abstract":"<div><div>This paper examines the NEET phenomenon as a socioeconomic epidemic. It addresses NEET dynamics at both the population and individual levels in North Africa. We argue that NEET status is transmitted through ideational contact and propose that proximity to Europe and migration aspirations act as non-traditional factors in this transmission. The analysis draws on multiple data sources. From a cross-country perspective, we rely on the World Bank’s and SAHWA’s surveys covering 45 African countries. From an intra-country perspective, we draw on longitudinal data from the Moroccan National Employment Survey, the World Bank (2014–2022), and local administrative archives to analyze Morocco’s NEET dynamics as a representative case for North Africa.</div><div>This study makes several original contributions. First, it conceptualizes the NEET phenomenon as a socioeconomic epidemic that spreads among individuals through contact with other NEETs. Second, it adapts the Susceptible–Infected–Recovered (SIR) model to analyze NEET dynamics in Morocco. This innovative approach allows us to construct the basic reproduction number (<span><math><msub><mrow><mi>R</mi></mrow><mrow><mn>0</mn></mrow></msub></math></span>) and to identify thresholds that govern NEET trends: stagnation, extinction, and persistence. Theoretically, this approach demonstrates the relevance of epidemiological modeling in explaining how socioeconomic phenomena like NEETs spread and persist. Practically, it identifies a critical threshold for policymakers, beyond which the spread of NEETs becomes difficult to reverse.</div><div>The findings further show that proximity to major economic centers and strong migration aspirations contribute to the expansion of NEETs. This underscores the need for integrated policy responses to curb the growth of NEET populations in their origin countries and prevent their effects from spilling over into destination countries.</div></div>","PeriodicalId":21690,"journal":{"name":"Scientific African","volume":"31 ","pages":"Article e03219"},"PeriodicalIF":3.3,"publicationDate":"2026-01-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146077786","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-28DOI: 10.1016/j.sciaf.2026.e03203
Kevin Otieno , Linda Chaba , Evans Omondi , Collins Odhiambo , Bernard Omolo
In dependence modeling, choosing the right copula is crucial, as different copula models can yield distinct interpretations of the relationship between variables. However, real-world applications are often constrained by the limitations of existing copula selection methods, which lack consistency and robustness across datasets. The selection methods in the literature that includes goodness-of-fit (GoF) tests and selection criteria, often yield conflicting results, thereby misrepresenting the dependence structure and leading to misleading conclusions. This study developed an integrated copula selection framework that combines GOF tests with cross-validation techniques. We integrated block-based cross-validation with GoF tests, where data was partitioned into blocks of different sizes . A copula was fitted on the training set, and its performance was validated on the test set using GoF measures. The selection process was repeated across multiple folds, and an aggregation method was applied to determine the most suitable copula. The approach was tested through Monte Carlo simulations and an empirical study was tested on weather variables in Kenya. The findings show that Kendall-based Kolmogorov–Smirnov (KendallKS) and Cramér–von Mises (KendallCvM) test statistics integrated with stratified cross-validation, when , perform better when the Benjamini–Hochberg (BH) procedure was used for aggregation. The proposed tests successfully identified the true copula and consistently rejected incorrect alternatives, with performance improving as sample size and dependence level increased. The empirical application further demonstrates the method’s robustness in real-world settings. These findings demonstrate that the proposed approach enhances the reliability and stability of copula selection.
在依赖建模中，选择正确的联结模型是至关重要的，因为不同的联结模型可以对变量之间的关系产生不同的解释。然而，现实世界的应用经常受到现有的copula选择方法的限制，这些方法缺乏跨数据集的一致性和鲁棒性。文献中的选择方法包括拟合优度（GoF）检验和选择标准，往往产生相互矛盾的结果，从而歪曲了依赖结构并导致误导性结论。本研究开发了一个综合的copula选择框架，将GOF测试与交叉验证技术相结合。我们将基于块的交叉验证与GoF测试相结合，其中数据被划分为不同大小(K)的块。在训练集上拟合了一个copula，并使用GoF度量在测试集上验证了其性能。选择过程在多个折叠中重复进行，并采用聚集法确定最合适的copula。通过蒙特卡洛模拟对该方法进行了测试，并对肯尼亚的天气变量进行了实证研究。结果表明，当K=5时，使用Benjamini-Hochberg （BH）程序进行聚合时，Kendall-based Kolmogorov-Smirnov （KendallKS）和cram - von Mises （KendallCvM）检验统计量与分层交叉验证相结合，表现更好。所提出的测试成功地识别了真正的联结，并始终拒绝不正确的替代方案，随着样本量和依赖程度的增加，性能也在提高。实证应用进一步证明了该方法在现实世界中的鲁棒性。这些结果表明，该方法提高了交配体选择的可靠性和稳定性。
{"title":"Integrating GOF tests and cross validation for copula model selection","authors":"Kevin Otieno , Linda Chaba , Evans Omondi , Collins Odhiambo , Bernard Omolo","doi":"10.1016/j.sciaf.2026.e03203","DOIUrl":"10.1016/j.sciaf.2026.e03203","url":null,"abstract":"<div><div>In dependence modeling, choosing the right copula is crucial, as different copula models can yield distinct interpretations of the relationship between variables. However, real-world applications are often constrained by the limitations of existing copula selection methods, which lack consistency and robustness across datasets. The selection methods in the literature that includes goodness-of-fit (GoF) tests and selection criteria, often yield conflicting results, thereby misrepresenting the dependence structure and leading to misleading conclusions. This study developed an integrated copula selection framework that combines GOF tests with cross-validation techniques. We integrated block-based cross-validation with GoF tests, where data was partitioned into blocks of different sizes <span><math><mrow><mo>(</mo><mi>K</mi><mo>)</mo></mrow></math></span>. A copula was fitted on the training set, and its performance was validated on the test set using GoF measures. The selection process was repeated across multiple folds, and an aggregation method was applied to determine the most suitable copula. The approach was tested through Monte Carlo simulations and an empirical study was tested on weather variables in Kenya. The findings show that Kendall-based Kolmogorov–Smirnov (KendallKS) and Cramér–von Mises (KendallCvM) test statistics integrated with stratified cross-validation, when <span><math><mrow><mi>K</mi><mo>=</mo><mn>5</mn></mrow></math></span>, perform better when the Benjamini–Hochberg (BH) procedure was used for aggregation. The proposed tests successfully identified the true copula and consistently rejected incorrect alternatives, with performance improving as sample size and dependence level increased. The empirical application further demonstrates the method’s robustness in real-world settings. These findings demonstrate that the proposed approach enhances the reliability and stability of copula selection.</div></div>","PeriodicalId":21690,"journal":{"name":"Scientific African","volume":"31 ","pages":"Article e03203"},"PeriodicalIF":3.3,"publicationDate":"2026-01-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146077787","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This study was conducted to investigate the integration of a Hydraulic Variable Valve Actuation (HVVA) system into a Lifan 177F single-cylinder gasoline engine to enhance performance, fuel efficiency, and emissions control. Unlike conventional valve mechanisms, HVVA systems are designed to dynamically adjust valve timing and lift through hydraulic actuation, allowing combustion to be optimized across a range of engine loads and speeds. MATLAB and GT-Suite simulations were used to model and evaluate the behavior of various valve spring configurations, including single-valve, dual-valve, and double-spring pendulum designs under dynamic operating conditions. It was found that engine power output was increased by 10%, fuel consumption was reduced by 5.64%, and torque delivery was significantly improved at mid to high RPM ranges. Among the configurations examined, the double-spring pendulum mechanism was shown to be the most effective in minimizing hydraulic oscillations, improving valve stability, and enabling smoother operation at higher speeds. These results highlight the practical potential of HVVA systems for use in compact and cost-sensitive engine platforms, where compliance with stringent emissions regulations and improved efficiency are increasingly demanded. Through precise and adaptive valve control, the proposed HVVA approach is shown to support cleaner combustion and align with broader sustainability objectives. In future work, efforts will be directed toward overcoming integration challenges and refining control strategies to further optimize HVVA system performance in practical automotive applications.
{"title":"Performance enhancement of a single-cylinder gasoline engine through hydraulic variable valve actuation (HVVA) system integration","authors":"Dimamu Biru, kumlachew Yeneneh, Bisrat Yoseph, Tatek Mamo","doi":"10.1016/j.sciaf.2026.e03196","DOIUrl":"10.1016/j.sciaf.2026.e03196","url":null,"abstract":"<div><div>This study was conducted to investigate the integration of a Hydraulic Variable Valve Actuation (HVVA) system into a Lifan 177F single-cylinder gasoline engine to enhance performance, fuel efficiency, and emissions control. Unlike conventional valve mechanisms, HVVA systems are designed to dynamically adjust valve timing and lift through hydraulic actuation, allowing combustion to be optimized across a range of engine loads and speeds. MATLAB and GT-Suite simulations were used to model and evaluate the behavior of various valve spring configurations, including single-valve, dual-valve, and double-spring pendulum designs under dynamic operating conditions. It was found that engine power output was increased by 10%, fuel consumption was reduced by 5.64%, and torque delivery was significantly improved at mid to high RPM ranges. Among the configurations examined, the double-spring pendulum mechanism was shown to be the most effective in minimizing hydraulic oscillations, improving valve stability, and enabling smoother operation at higher speeds. These results highlight the practical potential of HVVA systems for use in compact and cost-sensitive engine platforms, where compliance with stringent emissions regulations and improved efficiency are increasingly demanded. Through precise and adaptive valve control, the proposed HVVA approach is shown to support cleaner combustion and align with broader sustainability objectives. In future work, efforts will be directed toward overcoming integration challenges and refining control strategies to further optimize HVVA system performance in practical automotive applications.</div></div>","PeriodicalId":21690,"journal":{"name":"Scientific African","volume":"31 ","pages":"Article e03196"},"PeriodicalIF":3.3,"publicationDate":"2026-01-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146077792","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Electronic voting (e-voting) is increasingly recognized as a viable alternative to traditional paper-based elections, offering automation, transparency, and improved accessibility. However, blockchain-based e-voting frameworks still face critical challenges, notably excessive energy consumption, scalability bottlenecks, and trade-offs between performance and security. This paper proposes a sustainable hybrid cryptographic framework that integrates the Elliptic Curve Digital Signature Algorithm (ECDSA), the Edwards-Curve Digital Signature Algorithm (EdDSA), and Boneh–Lynn–Shacham (BLS) signatures. The proposed design reduces computational and energy overhead through lightweight ballot signing and aggregated verification, while ensuring interoperability with widely deployed blockchain infrastructures. Moreover, the framework incorporates Layer-2 batching within a Proof-of-Stake (PoS) consensus mechanism to minimize transaction costs and latency. Experimental results show that the proposed system reduces per-transaction energy consumption by nearly 50%, doubles transaction throughput from 120 to 250 TPS, and enhances scalability compared to conventional blockchain voting solutions. These findings confirm that hybrid cryptography represents a sustainable and practical pathway towards secure, transparent, and energy-efficient blockchain-based e-voting systems applicable to both institutional and national contexts.
{"title":"A sustainable hybrid cryptographic framework for energy optimization and scalability in blockchain-based e-voting","authors":"Adil Marouan , Morad Badrani , Abderrahim Zannou , Nabil Kannouf , Abdelaziz Chetouani","doi":"10.1016/j.sciaf.2026.e03191","DOIUrl":"10.1016/j.sciaf.2026.e03191","url":null,"abstract":"<div><div>Electronic voting (e-voting) is increasingly recognized as a viable alternative to traditional paper-based elections, offering automation, transparency, and improved accessibility. However, blockchain-based e-voting frameworks still face critical challenges, notably excessive energy consumption, scalability bottlenecks, and trade-offs between performance and security. This paper proposes a sustainable hybrid cryptographic framework that integrates the Elliptic Curve Digital Signature Algorithm (ECDSA), the Edwards-Curve Digital Signature Algorithm (EdDSA), and Boneh–Lynn–Shacham (BLS) signatures. The proposed design reduces computational and energy overhead through lightweight ballot signing and aggregated verification, while ensuring interoperability with widely deployed blockchain infrastructures. Moreover, the framework incorporates Layer-2 batching within a Proof-of-Stake (PoS) consensus mechanism to minimize transaction costs and latency. Experimental results show that the proposed system reduces per-transaction energy consumption by nearly 50%, doubles transaction throughput from 120 to 250 TPS, and enhances scalability compared to conventional blockchain voting solutions. These findings confirm that hybrid cryptography represents a sustainable and practical pathway towards secure, transparent, and energy-efficient blockchain-based e-voting systems applicable to both institutional and national contexts.</div></div>","PeriodicalId":21690,"journal":{"name":"Scientific African","volume":"31 ","pages":"Article e03191"},"PeriodicalIF":3.3,"publicationDate":"2026-01-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146077791","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-24DOI: 10.1016/j.sciaf.2026.e03190
Rachid Haloui , Amine Ballari , Khadija Khaddam Allah , Ayoub El-Mrabet , Abdelmoula El Abbouchi , Samir Chtita , Ahmed Mazzah , Amal Haoudi , Souad Elkhattabi
Human dihydroorotate dehydrogenase (DHODH) is a therapeutic target for the treatment of rheumatoid arthritis (RA). The development of new DHODH inhibitors could facilitate the discovery of a drug for RA therapy and contribute to sustainable health by promoting the design of safer and more efficient treatments. Using 3D-QSAR modeling techniques, we established a quantitative relationship between the DHODH inhibitory activity of 35 acrylamide derivatives (M1-M35) and their molecular fields. This model guided the design of 22 new acrylamide-based molecules (P1-P22) predicted to exhibit higher activity than M35, the most active in the initial database. The designed molecules were then docked into the DHODH active site, and the resulting complexes were evaluated using MM-GBSA free binding energy calculations. These analyses identified P4, P11, and P18 as the most DHODH inhibitors with docking scores and binding free energies superior to those of M35. The ADMET properties of the P4, P11, and P18 molecules were also predicted. The results show that they have good pharmacokinetic properties and are non-toxic. The molecular dynamics simulations of both free DHODH and its complexes with the best candidates confirmed the stability and validity of the obtained results. Finally, molecules P4, P11, and P18 show excellent capacity to inhibit the DHODH protein for the treatment of RA.
{"title":"Structure-based design and computational evaluation of new acrylamide derivatives as potent inhibitors of human dihydroorotate dehydrogenase for the treatment of rheumatoid arthritis","authors":"Rachid Haloui , Amine Ballari , Khadija Khaddam Allah , Ayoub El-Mrabet , Abdelmoula El Abbouchi , Samir Chtita , Ahmed Mazzah , Amal Haoudi , Souad Elkhattabi","doi":"10.1016/j.sciaf.2026.e03190","DOIUrl":"10.1016/j.sciaf.2026.e03190","url":null,"abstract":"<div><div>Human dihydroorotate dehydrogenase (DHODH) is a therapeutic target for the treatment of rheumatoid arthritis (RA). The development of new DHODH inhibitors could facilitate the discovery of a drug for RA therapy and contribute to sustainable health by promoting the design of safer and more efficient treatments. Using 3D-QSAR modeling techniques, we established a quantitative relationship between the DHODH inhibitory activity of 35 acrylamide derivatives (M1-M35) and their molecular fields. This model guided the design of 22 new acrylamide-based molecules (P1-P22) predicted to exhibit higher activity than M35, the most active in the initial database. The designed molecules were then docked into the DHODH active site, and the resulting complexes were evaluated using MM-GBSA free binding energy calculations. These analyses identified P4, P11, and P18 as the most DHODH inhibitors with docking scores and binding free energies superior to those of M35. The ADMET properties of the P4, P11, and P18 molecules were also predicted. The results show that they have good pharmacokinetic properties and are non-toxic. The molecular dynamics simulations of both free DHODH and its complexes with the best candidates confirmed the stability and validity of the obtained results. Finally, molecules P4, P11, and P18 show excellent capacity to inhibit the DHODH protein for the treatment of RA.</div></div>","PeriodicalId":21690,"journal":{"name":"Scientific African","volume":"31 ","pages":"Article e03190"},"PeriodicalIF":3.3,"publicationDate":"2026-01-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146077789","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-21DOI: 10.1016/j.sciaf.2026.e03189
Najat Gaidi , Abdelghafour EL Mekkaouy , Lamiae Talha , Mohammed Filali , Samir Chtita , Rodouan Touti
Lead-free halide double perovskites are promising alternatives to toxic Pb-based absorbers, yet the impact of alkali-metal substitution on lattice stability and optoelectronic response remains unclear. Here, first-principles calculations are employed to investigate the structural, lattice-dynamical, electronic, optical, and photovoltaic properties of cubic X2SbAgBr6 (X = Li, Na, K). All compounds satisfy the Born mechanical stability criteria, whereas phonon dispersions reveal that only Li2SbAgBr6 is dynamically stable at 0 K, while Na2SbAgBr6 and K2SbAgBr6 exhibit soft modes associated with octahedral tilting. Indirect band gaps in the range 0.75–0.81 eV and strong near-infrared absorption are obtained, with visible absorption arising from higher-energy interband transitions. These results identify Li2SbAgBr6 as the most robust cubic phase and demonstrate that A-site cation engineering provides an effective route to tune lattice stability and optoelectronic properties in lead-free double perovskites.
{"title":"First-principles insights into lead-free double perovskites X2SbAgBr6 (X = Li, Na, K) for sustainable optoelectronic applications","authors":"Najat Gaidi , Abdelghafour EL Mekkaouy , Lamiae Talha , Mohammed Filali , Samir Chtita , Rodouan Touti","doi":"10.1016/j.sciaf.2026.e03189","DOIUrl":"10.1016/j.sciaf.2026.e03189","url":null,"abstract":"<div><div>Lead-free halide double perovskites are promising alternatives to toxic Pb-based absorbers, yet the impact of alkali-metal substitution on lattice stability and optoelectronic response remains unclear. Here, first-principles calculations are employed to investigate the structural, lattice-dynamical, electronic, optical, and photovoltaic properties of cubic X<sub>2</sub>SbAgBr<sub>6</sub> (X = Li, Na, K). All compounds satisfy the Born mechanical stability criteria, whereas phonon dispersions reveal that only Li<sub>2</sub>SbAgBr<sub>6</sub> is dynamically stable at 0 K, while Na<sub>2</sub>SbAgBr<sub>6</sub> and K<sub>2</sub>SbAgBr<sub>6</sub> exhibit soft modes associated with octahedral tilting. Indirect band gaps in the range 0.75–0.81 eV and strong near-infrared absorption are obtained, with visible absorption arising from higher-energy interband transitions. These results identify Li<sub>2</sub>SbAgBr<sub>6</sub> as the most robust cubic phase and demonstrate that A-site cation engineering provides an effective route to tune lattice stability and optoelectronic properties in lead-free double perovskites.</div></div>","PeriodicalId":21690,"journal":{"name":"Scientific African","volume":"31 ","pages":"Article e03189"},"PeriodicalIF":3.3,"publicationDate":"2026-01-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146037477","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-19DOI: 10.1016/j.sciaf.2026.e03187
Zaynab EL KRIMI , El Mehdi EL KHATTABI , Sofia CHERIFZAOUI , Mohamed AIT ALAMA , Mohammed BOUSSETTA , Mourad BOUTAHIR , Mohammed ZOUINI
This study investigates the influence of building orientation and glazing type on indoor thermal performance across six Moroccan cities representing different climatic zones; lies in the comparative quantification of thermal comfort duration and amplitude across orientations and climate zones, rather than simply confirming directional trends. A dynamic thermal simulation was carried out using a simplified multi-zone residential building model developed in Python to evaluate daily indoor temperature variations under winter and summer conditions. The results reveal a strong dependence of indoor thermal behavior on both orientation and glazing configuration, showing that indoor temperature can vary by up to 8–10 °C between orientations in extreme climates, emphasizing the crucial role of solar exposure. The south-facing apartment generally provides the best thermal comfort in both seasons, with average indoor temperatures closest to the comfort range (18–26 °C), while the east and north orientations show less favorable conditions, particularly in winter. The glazing analysis shows that triple glazing significantly reduces daily temperature fluctuations and mitigates summer overheating in hot climates such as Marrakesh and Errachidia, whereas double glazing performs more effectively in cold climates such as Ifrane, where heating demand dominates. Across all cities, single glazing exhibits the greatest thermal instability and the lowest comfort duration. The results highlight that the optimal configuration varies with climate, and that apartment selection should first consider orientation, followed by an adapted glazing choice based on the dominant seasonal load: cooling for coastal and hot-arid zones, heating for mountainous regions, and a slight cooling dominance in Fes. Overall, the study provides a practical decision framework to help occupants and designers identify the most comfortable apartment configuration and reduce reliance on active heating and cooling systems in Moroccan residential buildings.
{"title":"Impact of orientation and glazing type on indoor thermal performance: A case study of a multi-apartment building under Moroccan climatic zones","authors":"Zaynab EL KRIMI , El Mehdi EL KHATTABI , Sofia CHERIFZAOUI , Mohamed AIT ALAMA , Mohammed BOUSSETTA , Mourad BOUTAHIR , Mohammed ZOUINI","doi":"10.1016/j.sciaf.2026.e03187","DOIUrl":"10.1016/j.sciaf.2026.e03187","url":null,"abstract":"<div><div>This study investigates the influence of building orientation and glazing type on indoor thermal performance across six Moroccan cities representing different climatic zones; lies in the comparative quantification of thermal comfort duration and amplitude across orientations and climate zones, rather than simply confirming directional trends. A dynamic thermal simulation was carried out using a simplified multi-zone residential building model developed in Python to evaluate daily indoor temperature variations under winter and summer conditions. The results reveal a strong dependence of indoor thermal behavior on both orientation and glazing configuration, showing that indoor temperature can vary by up to 8–10 °C between orientations in extreme climates, emphasizing the crucial role of solar exposure. The south-facing apartment generally provides the best thermal comfort in both seasons, with average indoor temperatures closest to the comfort range (18–26 °C), while the east and north orientations show less favorable conditions, particularly in winter. The glazing analysis shows that triple glazing significantly reduces daily temperature fluctuations and mitigates summer overheating in hot climates such as Marrakesh and Errachidia, whereas double glazing performs more effectively in cold climates such as Ifrane, where heating demand dominates. Across all cities, single glazing exhibits the greatest thermal instability and the lowest comfort duration. The results highlight that the optimal configuration varies with climate, and that apartment selection should first consider orientation, followed by an adapted glazing choice based on the dominant seasonal load: cooling for coastal and hot-arid zones, heating for mountainous regions, and a slight cooling dominance in Fes. Overall, the study provides a practical decision framework to help occupants and designers identify the most comfortable apartment configuration and reduce reliance on active heating and cooling systems in Moroccan residential buildings.</div></div>","PeriodicalId":21690,"journal":{"name":"Scientific African","volume":"31 ","pages":"Article e03187"},"PeriodicalIF":3.3,"publicationDate":"2026-01-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146037389","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-13DOI: 10.1016/j.sciaf.2026.e03183
Chelea Matchawe , Célestin Godwe , Clarisse Engowei Mbah , Tata B. Ndakoh , Mélanie F.K. Gondam , Henriette A. Essomba , Fadimatou Ahmadou , Manuela A. Baomog , Mélissa Wangue , Séverin Loul , Marie-Chantal Ngondé , Bonglaisin J. Nsawir , Lucy M. Ndip , Marco Galeotti , Edi Piasentier
Salmonella contamination of beef carcasses remains a major public health concern, particularly in low- and middle-income countries where abattoir hygiene and traceability systems are often inadequate. This study aimed to generate context-specific data on Salmonella contamination along the cattle slaughter chain at the Yaoundé abattoir using real-time PCR, and to evaluate the influence of zootechnical factors of slaughtered cattle within a One Health framework. A total of 705 swab samples were collected from live cattle (n = 145), carcasses (n = 310), butchers’ hands (n = 145), and meat contact surfaces (n = 105). Salmonella detection was performed using TaqMan probe-based real-time PCR. Overall, 14.9% (95% CI: 12.4%–17.6%) of samples were positive for Salmonella, with prevalence rates of 5.20% (95% CI: 2.4%–10.6%) in live cattle, 17.73% (95% CI: 13.89%–22.38%) in carcasses, 1.9% (95% CI: 0.52% – 6.68%) in contact surfaces, and 5.52% (95% CI: 2.8% – 10.5%) in butchers’ hand swabs. Salmonella occurrence differed significantly among sample categories (p < 0.05). However, multivariate logistic regression revealed that none of the assessed zootechnical factors (sex, age, breed, transport, origin, cleanliness, body condition, and production system) were independently associated with contamination (p > 0.05). These findings suggest that Salmonella contamination in slaughtered cattle is driven by systemic hygiene and biosecurity shortcomings rather than individual animal-related factors. Overall, the moderate prevalence observed reflects gaps in slaughter hygiene and biosecurity. Strengthening sanitation practices, enforcing Hazard Analysis and Critical Control Point (HACCP) measures, and adopting molecular surveillance tools such as real-time PCR are essential to reduce contamination risks and protect public health.
{"title":"Impacts of zootechnical factors on Salmonella contamination in swab samples using real-time PCR at the Yaounde slaughterhouse","authors":"Chelea Matchawe , Célestin Godwe , Clarisse Engowei Mbah , Tata B. Ndakoh , Mélanie F.K. Gondam , Henriette A. Essomba , Fadimatou Ahmadou , Manuela A. Baomog , Mélissa Wangue , Séverin Loul , Marie-Chantal Ngondé , Bonglaisin J. Nsawir , Lucy M. Ndip , Marco Galeotti , Edi Piasentier","doi":"10.1016/j.sciaf.2026.e03183","DOIUrl":"10.1016/j.sciaf.2026.e03183","url":null,"abstract":"<div><div><em>Salmonella</em> contamination of beef carcasses remains a major public health concern, particularly in low- and middle-income countries where abattoir hygiene and traceability systems are often inadequate. This study aimed to generate context-specific data on Salmonella contamination along the cattle slaughter chain at the Yaoundé abattoir using real-time PCR, and to evaluate the influence of zootechnical factors of slaughtered cattle within a One Health framework. A total of 705 swab samples were collected from live cattle (<em>n</em> = 145), carcasses (<em>n</em> = 310), butchers’ hands (<em>n</em> = 145), and meat contact surfaces (<em>n</em> = 105). <em>Salmonella</em> detection was performed using TaqMan probe-based real-time PCR. Overall, 14.9% (95% CI: 12.4%–17.6%) of samples were positive for <em>Salmonella</em>, with prevalence rates of 5.20% (95% CI: 2.4%–10.6%) in live cattle, 17.73% (95% CI: 13.89%–22.38%) in carcasses, 1.9% (95% CI: 0.52% – 6.68%) in contact surfaces, and 5.52% (95% CI: 2.8% – 10.5%) in butchers’ hand swabs. <em>Salmonella</em> occurrence differed significantly among sample categories (<em>p</em> < 0.05). However, multivariate logistic regression revealed that none of the assessed zootechnical factors (sex, age, breed, transport, origin, cleanliness, body condition, and production system) were independently associated with contamination (<em>p</em> > 0.05). These findings suggest that <em>Salmonella</em> contamination in slaughtered cattle is driven by systemic hygiene and biosecurity shortcomings rather than individual animal-related factors. Overall, the moderate prevalence observed reflects gaps in slaughter hygiene and biosecurity. Strengthening sanitation practices, enforcing Hazard Analysis and Critical Control Point (HACCP) measures, and adopting molecular surveillance tools such as real-time PCR are essential to reduce contamination risks and protect public health.</div></div>","PeriodicalId":21690,"journal":{"name":"Scientific African","volume":"31 ","pages":"Article e03183"},"PeriodicalIF":3.3,"publicationDate":"2026-01-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146077844","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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