Scientific African最新文献

英文中文

Valorization of date palm residues for biochar production: Assessing biochar characteristics for agricultural application

IF 2.7 Q2 MULTIDISCIPLINARY SCIENCES

Scientific African

Pub Date : 2025-03-01 DOI: 10.1016/j.sciaf.2025.e02599

Mariyem Rehali , Naïma El Ghachtouli , Sébastien F. Lange , Rachid Bouamri

Date palm residues are abundant in many arid and semi-arid regions, presenting both an environmental challenge and an opportunity for sustainable resource management. This study evaluates the valorization of date palm residues through slow pyrolysis at 500 °C to produce biochar suitable for agricultural soil enhancement. The date palm residues, which consist of 41.95% cellulose, 28.49% hemicellulose, and 26.56% lignin, were processed to yield biochar with a production efficiency of 44.95%. The biochar's physicochemical properties were extensively analyzed, showing a fixed carbon content of 70.74%, a pH of 9.19, and a cation exchange capacity (CEC) of 68.05 cmol/kg. Elemental analysis revealed high carbon (71.9%) and low nitrogen (0.74%) content, indicating its stability and potential for long-term carbon sequestration. Thermogravimetric analysis (TGA) indicated thermal stability, while scanning electron microscopy (SEM) revealed a highly porous structure, beneficial for water retention and microbial colonization. These findings demonstrate that the slow pyrolysis process yields biochar with favorable properties, making it a promising amendment for soil fertilization. This study highlights the potential of biochar production in transforming date palm waste into valuable resources while mitigating the environmental impacts and costs associated with its disposal.

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引用次数: 0

In vivo anti-inflammatory activity, acute toxicity profiling, and sub-acute toxicity profiling of extracts from the fruit pulp and seeds of african baobab (Adansonia digitata L.) 非洲猴面包树（Adansonia digitata L.）果肉和种子提取物的体内抗炎活性、急性毒性分析和亚急性毒性分析

IF 2.7 Q2 MULTIDISCIPLINARY SCIENCES

Scientific African

Pub Date : 2025-03-01 DOI: 10.1016/j.sciaf.2025.e02615

Mercy Badu , Philip T. Thompson , Vivian E. Boamah

Adansonia digitata (L.) is an ancient plant widely known for its diverse medicinal properties. The pulp and seeds of this plant are commonly consumed by rural populations in Africa, valued for their poly-therapeutic benefits. This study investigates the anti-inflammatory activity, acute toxicity, and sub-acute toxicity of extracts from the pulp and seeds using animal models. The anti-inflammatory potential was assessed using a carrageenan-induced foot edema model in 7-day-old chicks, while the acute and sub-acute toxicities were evaluated in Wistar albino rats. In the anti-inflammatory study, the fruit pulp extract exhibited an ED₅₀ value of 282.12 mg/kg BW, while the seed extracts showed similar activity with ED₅₀ values of 338.41 mg/kg BW for the polar extract and 347.40 mg/kg BW for the non-polar extract. In the acute toxicity evaluation, no mortality was observed at the highest administered dose of 5000 mg/kg BW, suggesting an LD₅₀ value above the highest administered dose. Sub-acute toxicity studies over 28 days revealed significant increases (p < 0.05) in body weight, absolute organ weight, and relative organ weight in rats, yet without adverse effects on hematological or biochemical parameters. Histopathological analysis confirmed the absence of damage to kidney and liver tissues, indicating the safety of the extracts at doses below the estimated LD₅₀. In conclusion, the extracts demonstrate notable anti-inflammatory activity and appear safe for consumption within the tested dose range, supporting their traditional use for health benefits.

{"title":"In vivo anti-inflammatory activity, acute toxicity profiling, and sub-acute toxicity profiling of extracts from the fruit pulp and seeds of african baobab (Adansonia digitata L.)","authors":"Mercy Badu , Philip T. Thompson , Vivian E. Boamah","doi":"10.1016/j.sciaf.2025.e02615","DOIUrl":"10.1016/j.sciaf.2025.e02615","url":null,"abstract":"<div><div><em>Adansonia digitata</em> (L.) is an ancient plant widely known for its diverse medicinal properties. The pulp and seeds of this plant are commonly consumed by rural populations in Africa, valued for their poly-therapeutic benefits. This study investigates the anti-inflammatory activity, acute toxicity, and sub-acute toxicity of extracts from the pulp and seeds using animal models. The anti-inflammatory potential was assessed using a carrageenan-induced foot edema model in 7-day-old chicks, while the acute and sub-acute toxicities were evaluated in Wistar albino rats. In the anti-inflammatory study, the fruit pulp extract exhibited an ED<sub>50</sub> value of 282.12 mg/kg BW, while the seed extracts showed similar activity with ED<sub>50</sub> values of 338.41 mg/kg BW for the polar extract and 347.40 mg/kg BW for the non-polar extract. In the acute toxicity evaluation, no mortality was observed at the highest administered dose of 5000 mg/kg BW, suggesting an LD<sub>50</sub> value above the highest administered dose. Sub-acute toxicity studies over 28 days revealed significant increases (p < 0.05) in body weight, absolute organ weight, and relative organ weight in rats, yet without adverse effects on hematological or biochemical parameters. Histopathological analysis confirmed the absence of damage to kidney and liver tissues, indicating the safety of the extracts at doses below the estimated LD<sub>50</sub>. In conclusion, the extracts demonstrate notable anti-inflammatory activity and appear safe for consumption within the tested dose range, supporting their traditional use for health benefits.</div></div>","PeriodicalId":21690,"journal":{"name":"Scientific African","volume":"27 ","pages":"Article e02615"},"PeriodicalIF":2.7,"publicationDate":"2025-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143527064","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

Unit exponentiated Weibull model with applications

IF 2.7 Q2 MULTIDISCIPLINARY SCIENCES

Scientific African

Pub Date : 2025-03-01 DOI: 10.1016/j.sciaf.2025.e02606

Ammar M. Sarhan , M.E. Sobh

Developing new effective statistical distributions tailored to model data on the unit interval is essential in modern data analysis. In this article, we propose a novel distribution on the unit interval, termed the unit exponentiated Weibull distribution, derived from the three-parameter exponentiated Weibull distribution. We will explore the key statistical properties of this new distribution and employ the maximum likelihood and least squares methods for parameter estimation. A simulation study is conducted to evaluate the performance of the maximum likelihood and least squares estimates. The simulation study demonstrates that the maximum likelihood method outperforms the least squares method in estimating the three parameters of the underlying model. To illustrate the practical utility of the proposed model, we analyze real-world datasets and compare its performance against other established distributions. The results show that the proposed model provides a superior fit to the competing models considered in the study.

引用次数: 0

Insights into the optoelectronic, quantum chemical, NBO and dynamic nonlinear optical properties of meso-BODIPY dyes

IF 2.7 Q2 MULTIDISCIPLINARY SCIENCES

Scientific African

Pub Date : 2025-03-01 DOI: 10.1016/j.sciaf.2025.e02608

Oluwatoba Emmanuel Oyeneyin , Nathanael Damilare Ojo , Adesoji Alani Olanrewaju , Blessing Lully Isaiah , Nnenna Winifred Odozi , Edmore Farayi Kangara , Matshawandile Tukulula

Herein, understanding the effect of substituents on the electronic absorption, optoelectronic, static and dynamic nonlinear optical (NLO) properties, and molecular stability of (CF₃-, CH₃-, CCl₃-, NH₂-, NO₂-) meso-substituted BODIPY dyes was specifically aimed at using density functional (B3LYP and CAM-B3LYP) approach with 6–311++G(d,p). Solvent perturbation of electronic excitation energy, oscillator strength and light-harvesting efficiency (LHE) was observed. The LHE increased from 74–80% in gas to 87–90% in acetonitrile. The static first-order and second-order (β, γ) NLO properties of the dyes were significantly greater than those of urea (a standard NLO material). Interestingly, the dynamic NLO [electro-optic Pockels effect: β(-ω;ω,0); second harmonic generation (SHG): β(-2ω;ω,ω); electro-optic Kerr effect: γ(-ω;ω,0,0); direct current SHG: γ(-2ω;ω,ω,0)] at ħω = 0.042823 au were greater than the static β and γ (ħω = 0). NO₂- substituted dye presented greatest NLO amplitudes. Natural bond orbital (NBO) analysis identified conjugative and hyperconjugative interactions as the major contributors to the structural stabilization of the dyes. Except for NO₂-dye, a negative free energy for electron injection and a positive open-circuit voltage were observed indicating good optoelectronic potential of the substituted BODIPY in dye sensitized solar cells. The molecular instability, chemical reactivity (from energy gap) and dynamic NLO response of the dyes increased in the order: NH₂- < CH₃- < CF₃- < CCl₃ < NO₂-.

{"title":"Insights into the optoelectronic, quantum chemical, NBO and dynamic nonlinear optical properties of meso-BODIPY dyes","authors":"Oluwatoba Emmanuel Oyeneyin , Nathanael Damilare Ojo , Adesoji Alani Olanrewaju , Blessing Lully Isaiah , Nnenna Winifred Odozi , Edmore Farayi Kangara , Matshawandile Tukulula","doi":"10.1016/j.sciaf.2025.e02608","DOIUrl":"10.1016/j.sciaf.2025.e02608","url":null,"abstract":"<div><div>Herein, understanding the effect of substituents on the electronic absorption, optoelectronic, static and dynamic nonlinear optical (NLO) properties, and molecular stability of (CF<sub>3</sub>-, CH<sub>3</sub>-, CCl<sub>3</sub>-, NH<sub>2</sub>-, NO<sub>2</sub>-) meso-substituted BODIPY dyes was specifically aimed at using density functional (B3LYP and CAM-B3LYP) approach with 6–311++G(d,p). Solvent perturbation of electronic excitation energy, oscillator strength and light-harvesting efficiency (LHE) was observed. The LHE increased from 74–80% in gas to 87–90% in acetonitrile. The static first-order and second-order (β, γ) NLO properties of the dyes were significantly greater than those of urea (a standard NLO material). Interestingly, the dynamic NLO [electro-optic Pockels effect: β(-ω;ω,0); second harmonic generation (SHG): β(-2ω;ω,ω); electro-optic Kerr effect: γ(-ω;ω,0,0); direct current SHG: γ(-2ω;ω,ω,0)] at <em>ħω</em> = 0.042823 au were greater than the static β and γ (<em>ħω</em> = 0). NO<sub>2</sub>- substituted dye presented greatest NLO amplitudes. Natural bond orbital (NBO) analysis identified conjugative and hyperconjugative interactions as the major contributors to the structural stabilization of the dyes. Except for NO<sub>2</sub>-dye, a negative free energy for electron injection and a positive open-circuit voltage were observed indicating good optoelectronic potential of the substituted BODIPY in dye sensitized solar cells. The molecular instability, chemical reactivity (from energy gap) and dynamic NLO response of the dyes increased in the order: NH<sub>2</sub>- < CH<sub>3</sub>- < CF<sub>3</sub>- < CCl<sub>3</sub> < NO<sub>2</sub>-.</div></div>","PeriodicalId":21690,"journal":{"name":"Scientific African","volume":"27 ","pages":"Article e02608"},"PeriodicalIF":2.7,"publicationDate":"2025-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143579972","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

Huff’s form for elliptic curves over a local ring

IF 2.7 Q2 MULTIDISCIPLINARY SCIENCES

Scientific African

Pub Date : 2025-03-01 DOI: 10.1016/j.sciaf.2025.e02597

Abdelhakim Chillali , Moha Ben Taleb El Hamam , Abdelâli Grini

Let

F_{q}

be a finite field of order

q = p^{c}

, where

p

is a prime number

\geq 3

c \in N^{*}

. In this paper, we introduce Huff curves denoted

H_{a, b}^{2}

over the local ring

R_{2} = F_{q} [X] / (X^{2})

. At first, we recall the arithmetic of the ring

R_{2}

. After that, we define Huff curves

H_{a, b}^{2}

over this ring and we study the group

H_{a, b}^{2}

, its properties and the classification of its elements. Precisely, we give a bijection between the groups

H_{a, b}^{2}

and

H_{a_{0}, b_{0}} \times F_{q}

, where

H_{a_{0}, b_{0}}

is the Huff curves over the finite field

F_{q}

引用次数: 0

A bibliometric analysis on renewable energy microgrids integrating hydrogen storage: Strategies for optimal sizing and energy management

IF 2.7 Q2 MULTIDISCIPLINARY SCIENCES

Scientific African

Pub Date : 2025-03-01 DOI: 10.1016/j.sciaf.2025.e02609

Mukhtar Fatihu Hamza , Babangida Modu

Hydrogen is regarded as a viable alternative energy carrier because of its superior energy density and low emissions, with great potential for decarbonizing multiple sectors and improving energy sustainability by integrating into the existing energy systems and renewable energy source within the utility. This paper provides a bibliometric assessment through an extensive review of highly cited articles on hydrogen storage integrated microgrid. The study utilized the Web of Science (WoS) database to look for specific keywords related to hydrogen storage integrated microgrid and associated research. The findings reveal that optimization, highly positioned and connected to many other keywords, is demonstrating its importance in the research area. Notable insights highlight the dominance of simulation-based studies, a significant number of publications in top-tier journals, and the rise of innovative research fields, including the creation of sustainable electrodes and improvements in system reliability and efficiency. The evaluation of the articles that are highly cited sheds light on diverse elements, such as approach and system, challenges, and research spaces. This analysis shows ways to improve the performance of operation, energy efficiency, environmental sustainability, cost-effectiveness, stable supply of power, on-location energy generation, and flexibility, thereby advancing technological innovation and fostering the development of hydrogen storage-integrated microgrids.

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引用次数: 0

Mineralogical and petrographic characterisation of flake graphite in the graphite mica schist rocks from the Nubian Desert, Sudan

IF 2.7 Q2 MULTIDISCIPLINARY SCIENCES

Scientific African

Pub Date : 2025-03-01 DOI: 10.1016/j.sciaf.2025.e02602

Dalal Desouqi , Mohamad Amran Mohd Salleh , Muhammad Hatta Roselee , Aisyah M Yahya , Bushra Abdo Alsalam , Suraya Abdul Rashid

The Nubian Desert in Sudan, spanning from the Nile River in Wadi Halfa to the eastern Red Sea region, hosts graphite-bearing rocks that can potentially meet the increasing demand for natural graphite, a critical mineral in green energy technologies. This study is the first to investigate the detailed mineralogical and petrographic characteristics of graphite-bearing rocks from this region using petrography, scanning electron microscopy (SEM), energy-dispersive X-ray spectrometry (EDX), X-ray diffraction (XRD), and thermogravimetric analysis (TGA). The Nubian Desert flake graphite is of high-grade and hosted in metamorphic graphite schist that has been subjected to an increasing regional environment of amphibolite-to-greenschist facies. The schist is of high-grade and fine-grained, with a clear foliation texture composed of graphite (10 %), quartz (35 %), mica (biotite+muscovite) (50 %), and albite (5 %). Fine graphite flakes, ranging from 50 to 150 µm in length with an average width of 46 µm, are disseminated along the schist foliation texture. The quantitative elemental contents are C (10 %), SiO₂ (60 %), Al₂O₃ (20 %), and K₂O (10 %). Approximately 84 % of the total carbon is graphite, whereas 16 % is graphitised carbon, which can be upgraded by froth flotation and acid leaching. Although the crystallinity and microcrystal structure of the graphite require further investigation, the preliminary mineralogical features meet the international standards for high-grade fine-flake graphite and suggest its suitability for advanced processing and exploration. These findings highlight the Nubian Desert as an important and underexplored graphite resource, necessitating expanded geological and industrial investigations to meet the growing demand for critical minerals required for sustainable energy technologies.

{"title":"Mineralogical and petrographic characterisation of flake graphite in the graphite mica schist rocks from the Nubian Desert, Sudan","authors":"Dalal Desouqi , Mohamad Amran Mohd Salleh , Muhammad Hatta Roselee , Aisyah M Yahya , Bushra Abdo Alsalam , Suraya Abdul Rashid","doi":"10.1016/j.sciaf.2025.e02602","DOIUrl":"10.1016/j.sciaf.2025.e02602","url":null,"abstract":"<div><div>The Nubian Desert in Sudan, spanning from the Nile River in Wadi Halfa to the eastern Red Sea region, hosts graphite-bearing rocks that can potentially meet the increasing demand for natural graphite, a critical mineral in green energy technologies. This study is the first to investigate the detailed mineralogical and petrographic characteristics of graphite-bearing rocks from this region using petrography, scanning electron microscopy (SEM), energy-dispersive X-ray spectrometry (EDX), X-ray diffraction (XRD), and thermogravimetric analysis (TGA). The Nubian Desert flake graphite is of high-grade and hosted in metamorphic graphite schist that has been subjected to an increasing regional environment of amphibolite-to-greenschist facies. The schist is of high-grade and fine-grained, with a clear foliation texture composed of graphite (10 %), quartz (35 %), mica (biotite+muscovite) (50 %), and albite (5 %). Fine graphite flakes, ranging from 50 to 150 µm in length with an average width of 46 µm, are disseminated along the schist foliation texture. The quantitative elemental contents are C (10 %), SiO<sub>2</sub> (60 %), Al₂O₃ (20 %), and K₂O (10 %). Approximately 84 % of the total carbon is graphite, whereas 16 % is graphitised carbon, which can be upgraded by froth flotation and acid leaching. Although the crystallinity and microcrystal structure of the graphite require further investigation, the preliminary mineralogical features meet the international standards for high-grade fine-flake graphite and suggest its suitability for advanced processing and exploration. These findings highlight the Nubian Desert as an important and underexplored graphite resource, necessitating expanded geological and industrial investigations to meet the growing demand for critical minerals required for sustainable energy technologies.</div></div>","PeriodicalId":21690,"journal":{"name":"Scientific African","volume":"27 ","pages":"Article e02602"},"PeriodicalIF":2.7,"publicationDate":"2025-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143509307","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

Enhancement of bioconversion of vegetable biowaste by black soldier fly larvae: Influence of mechanical and thermomechanical pretreatments

IF 2.7 Q2 MULTIDISCIPLINARY SCIENCES

Scientific African

Pub Date : 2025-03-01 DOI: 10.1016/j.sciaf.2025.e02626

Younesse El-byari, Mohammed Bendriss Amraoui

In many countries, the growing production of biowaste poses a major environmental threat, requiring significant budgets for its management. This issue has driven the development of innovative valorisation methods, such as bioconversion. Black Soldier Fly Larvae (BSFL) present a promising solution, capable of converting biowaste into larval biomass rich in proteins and lipids. In this study, we evaluated the impact of mechanical and thermomechanical pre-treatments, combined with optimized substrate formulations, on the performance of BSFL. Thermomechanical pre-treatment significantly improved nutrient solubility, reduced inhibitory compounds such as polyphenols from orange peels, and enhanced larval growth compared to mechanical pre-treatment alone. Mixed substrates showed optimal performance, with a survival rate of 98.3 %, a bioconversion rate of 31.11 %, a reduced development time of 18 days, and a biowaste reduction efficiency of up to 83 %. However, coffee grounds, due to their high lignin content and recalcitrant compounds, exhibited low biodegradability and limited availability of soluble nutrients, even after thermomechanical pre-treatment. These results demonstrate that the use of mixed substrates, combined with appropriate pre-treatments, enables increased waste reduction and improved larval performance. This study highlights the importance of pre-treatment and substrate formulation in maximizing BSFL efficiency for biowaste valorization while promoting sustainable waste management and a circular bioeconomy.

{"title":"Enhancement of bioconversion of vegetable biowaste by black soldier fly larvae: Influence of mechanical and thermomechanical pretreatments","authors":"Younesse El-byari, Mohammed Bendriss Amraoui","doi":"10.1016/j.sciaf.2025.e02626","DOIUrl":"10.1016/j.sciaf.2025.e02626","url":null,"abstract":"<div><div>In many countries, the growing production of biowaste poses a major environmental threat, requiring significant budgets for its management. This issue has driven the development of innovative valorisation methods, such as bioconversion. Black Soldier Fly Larvae (BSFL) present a promising solution, capable of converting biowaste into larval biomass rich in proteins and lipids. In this study, we evaluated the impact of mechanical and thermomechanical pre-treatments, combined with optimized substrate formulations, on the performance of BSFL. Thermomechanical pre-treatment significantly improved nutrient solubility, reduced inhibitory compounds such as polyphenols from orange peels, and enhanced larval growth compared to mechanical pre-treatment alone. Mixed substrates showed optimal performance, with a survival rate of 98.3 %, a bioconversion rate of 31.11 %, a reduced development time of 18 days, and a biowaste reduction efficiency of up to 83 %. However, coffee grounds, due to their high lignin content and recalcitrant compounds, exhibited low biodegradability and limited availability of soluble nutrients, even after thermomechanical pre-treatment. These results demonstrate that the use of mixed substrates, combined with appropriate pre-treatments, enables increased waste reduction and improved larval performance. This study highlights the importance of pre-treatment and substrate formulation in maximizing BSFL efficiency for biowaste valorization while promoting sustainable waste management and a circular bioeconomy.</div></div>","PeriodicalId":21690,"journal":{"name":"Scientific African","volume":"27 ","pages":"Article e02626"},"PeriodicalIF":2.7,"publicationDate":"2025-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143548834","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

An experimental study of a high-gain, wideband circularly polarized printed antenna array at 2.45 GHz in the ISM band for wireless power transmission applications

IF 2.7 Q2 MULTIDISCIPLINARY SCIENCES

Scientific African

Pub Date : 2025-03-01 DOI: 10.1016/j.sciaf.2025.e02619

Walid En-naghma , Mohamed Latrach , Hanan Halaq , Abdelghani El Ougli

An enhanced wideband circularly polarized printed antenna array (CPPAA) is designed, analyzed, fabricated, and discussed in this paper. The proposed CPPAA structure is printed on a Flame Retardant (FR-4) material as a commercially available substrate. This CPPAA structure is simulated using two software which are CST MWS (Computer Simulation Technology Microwave Studio), and HFSS (High-Frequency Structure Simulator). The main goal behind these two solvers is to prove the effectiveness of this CPPAA. Then, it was fabricated and experimentally measured via the PNA-X Network Analyzer. The presented CPPAA operates at 2.45 GHz with the measured gain values of 7.80 dBi, the measured bandwidth is 290 MHz around 2.45 GHz (from 2.2844 GHz to 2.5744 GHz), and the measured efficiency is about 80.83 %. The VSWR of the fabricated prototype does not exceed the need of 1.5. The suggested CPPAA design can be suitable for energy harvesting and wireless power transmission applications, especially in rectenna systems construction.

{"title":"An experimental study of a high-gain, wideband circularly polarized printed antenna array at 2.45 GHz in the ISM band for wireless power transmission applications","authors":"Walid En-naghma , Mohamed Latrach , Hanan Halaq , Abdelghani El Ougli","doi":"10.1016/j.sciaf.2025.e02619","DOIUrl":"10.1016/j.sciaf.2025.e02619","url":null,"abstract":"<div><div>An enhanced wideband circularly polarized printed antenna array (CPPAA) is designed, analyzed, fabricated, and discussed in this paper. The proposed CPPAA structure is printed on a Flame Retardant (FR-4) material as a commercially available substrate. This CPPAA structure is simulated using two software which are CST MWS (Computer Simulation Technology Microwave Studio), and HFSS (High-Frequency Structure Simulator). The main goal behind these two solvers is to prove the effectiveness of this CPPAA. Then, it was fabricated and experimentally measured via the PNA-X Network Analyzer. The presented CPPAA operates at 2.45 GHz with the measured gain values of 7.80 dBi, the measured bandwidth is 290 MHz around 2.45 GHz (from 2.2844 GHz to 2.5744 GHz), and the measured efficiency is about 80.83 %. The VSWR of the fabricated prototype does not exceed the need of 1.5. The suggested CPPAA design can be suitable for energy harvesting and wireless power transmission applications, especially in rectenna systems construction.</div></div>","PeriodicalId":21690,"journal":{"name":"Scientific African","volume":"27 ","pages":"Article e02619"},"PeriodicalIF":2.7,"publicationDate":"2025-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143561991","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

Migration, factor mobility and economic complexity in African countries

IF 2.7 Q2 MULTIDISCIPLINARY SCIENCES

Scientific African

Pub Date : 2025-03-01 DOI: 10.1016/j.sciaf.2025.e02601

Solomon O. Okunade , Oyindamola O. Adeyemo , Oluwole J. Adeyemi , Evans Osabuohien

The African region's ability to diversify and become more complex economically is limited due to the low productive capacities and sophistication of the economies. For African countries, moving up the complexity ladder is critical for achieving sustainable development goals and reducing vulnerability to external shocks. This requires a critical examination of several macroeconomic factors, among which migration and factor mobility are substantial, especially where international factor movements remain almost uncontrollable. This empirical study therefore explores how migration and factor mobility influence economic complexity, diversification, and sophistication across low-, lower-middle-, and upper-middle-income African countries based on 2024 World Bank income classifications. The study employs panel-corrected standard errors (PCSE), feasible generalised least squares (FGLS), and the Dumitrescu-Hurlin non-causality test to achieve its objectives using a balanced panel of 34 African countries. The findings show that net migration generally hinders economic complexity, while remittances inflows enhance economic complexity in Africa especially in lower-middle-income countries. Also, foreign direct investment (FDI) inflows have no significant influence on economic complexity due to its concentration in the primary and extractive sectors, whereas FDI outflows promote it by fostering domestic firms' capabilities. Also, high net foreign assets hinder economic complexity due to capital being held abroad rather than invested domestically. The study contributes to knowledge by underscoring the need for policies that retain and effectively utilise domestic capital, mitigate brain drains, strategically attract FDI, and leverage remittances for productive investments. By addressing these factors, African countries can enhance their economic complexity, leading to more robust and diversified economies.

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