DSpace Community:

Simulation of unsteady magnetohydrodynamic flow of hybrid nanofluid in solar thermal collectors

2026-03-01T00:00:00Z

Title: Simulation of unsteady magnetohydrodynamic flow of hybrid nanofluid in solar thermal collectors Authors: Ndede, Charles O.; Ojiambo, Viona; Abonyo, Jeconia O.; Ngesa, Joel O. Abstract: The urgent challenge of climate change calls for innovative energy solutions that reduce greenhouse gas emissions and strengthen system resilience. Solar thermal technology, when enhanced by advanced fluid dynamics, offers a promising pathway towards sustainable clean energy. This study simulates the performance of hybrid nanofluids, specifically copper and titanium dioxide nanoparticles dispersed in water, to improve heat transfer efficiency in parabolic solar thermal collectors. The governing nonlinear partial differential equations describing mass, momentum, energy, concentration, and magnetic induction are reduced to ordinary differential equations using similarity transformations and solved using MATLAB’s collocation based bvp4c solver. The model assumes two-dimensional laminar flow, thermal equilibrium between fluid phases, and temperature dependent hybrid nanofluid properties. Parametric analysis shows that Brownian diffusion and thermophoresis significantly influence velocity, temperature, and nanoparticle concentration, while Prandtl and thermal Grashof numbers strongly govern convective transport and MHD coupling. The findings provide deeper physical insight into hybrid nanofluid dynamics under electromagnetic influences and support the optimization of solar thermal collectors for enhanced thermal performance. The study contributes to Sustainable Development Goals 13 by advancing efficient and climate resilient clean energy technologies.

Preliminary report of epicoccum spp. associated with brown leaf spot on cassava in Kenya

2026-01-01T00:00:00Z

Title: Preliminary report of epicoccum spp. associated with brown leaf spot on cassava in Kenya Authors: Onyango, Ephine A.; Kituyi, Sarah N.; Hunja, Carol W.; Kimatu, Josphert N.; Nyaboga, Evans N. Abstract: Cassava brown leaf spot (BLS) is among the most damaging diseases that significantly reduce cassava root yields and quality. In this study, drought-resistant cassava varieties were screened on an experimental farm in Kitui County, Kenya. One variety, Kasukari, exhibited abnormal morphological aberrations suggesting BLS and necessitated systematic studies to establish the causal agents. Fungi were isolated from symptomatic leaves and purified on Potato Dextrose Agar (PDA) with antibiotics. Fungal pathogens were identified using morpho-cultural characteristics and molecular characterization through polymerase chain reaction (PCR) amplification and sequencing of the internal transcribed spacer (ITS). 162 Kasukari samples were used to determine the prevalence and severity of the disease, while 15 samples were used to determine the effects of the disease. Pathogenicity tests of ten isolates were conducted in vitro using detached leaves of the healthy Kasukari variety. The results indicated that the prevalence within the plots had no significant difference (χ2 = 6, p-value = 0.1991). However, there was a significant difference in severity (χ2 = 53.013, p-value = 1.166e-09). PCR with the ITS marker identified the fungal pathogens from the genera Alternaria, Epicoccum, Preussia, and Cladosporium. Epicoccum spp. had colonies of white clusters that formed concentric rings, while the reverse had grey-brown colonies and a regular margin. Conidia produced on PDA were oval, hyaline, unicellular, and aseptate, consistent with Epicoccum morphology. Based on ITS identification and pathogenicity assays, this study provides a preliminary report of an Epicoccum sp. associated with brown leaf spot (BLS) disease in cassava in Kenya. However, due to the absence of multi-locus sequence data and the limited number of isolates tested, the causal role of Epicoccum remains suggestive. These findings form the basis for future studies to confirm the causal role of Epicoccum spp. and clarify its epidemiology. The study will also help inform prevention and management strategies, including breeding programs and targeted control measures. Description: https://doi.org/10.1016/j.heliyon.2026.e45093

Isolation and functional profiling of seed‐associated bacteria from rattlepods (crotalaria spp.) with biotechnological potential

2026-01-01T00:00:00Z

Title: Isolation and functional profiling of seed‐associated bacteria from rattlepods (crotalaria spp.) with biotechnological potential Authors: Odoi, Brenda A.; Nthiwa, Daniel M.; Neondo, Johnstone O .; Muli, Joshua K.; Kamau, Peter K.; Budambula, Nancy L. Abstract: Microorganisms associated with plant seeds have recently gained increased attention due to their pivotal role in enhancing plant health through the acquisition of nutrients and plant growth promotion. Although rattlepods (Crotalaria spp.) are widely consumed, information regarding the bacterial diversity and functional roles within their seeds remain unexplored. This study isolated, identified, and characterized endophytic and epiphytic culturable bacteria from seeds of Kenyan rattlepods. A total of 118 seed-associated bacterial isolates were cultured from the rattlepods (Crotalaria spp.), and 20 of them were identified using 16S rRNA gene sequencing. The isolates belonged to two distinct phyla: Proteobacteria and Firmicutes. The isolates belonged to four genera: nine Bacillus, nine Proteus, one Lysinibacillus, and one Morganella. BLAST analysis of partial 16S rRNA gene sequences (763-1273bp) showed that 19 of the 20 isolates exhibited high similarity (˃99%) to previously described species, whereas one isolate showed low similarity (< 0.05) higher protease and cellulase. Isolates 4EnA1/2/1 (P. mirabilis) and 9EnA (P. mirabilis) were the highest significant amylase producers, whereas isolates 3EnB3/3 (Proteus sp. [in enterobacteria]) and 10EnA 2/1 (P. mirabilis) were the highest significant lipase producers. Most seed-associated bacteria isolated from Crotalaria spp. were identified as known species; however, some isolates may represent novel taxa and could serve as promising candidates for the production of biotechnologically important extracellular enzymes under mesophilic conditions. Description: https://doi.org/10.1155/ijm/6560468

Trends in demographic and health survey publications based on a bibliometric analysis

2026-06-01T00:00:00Z

Title: Trends in demographic and health survey publications based on a bibliometric analysis Authors: Omondi, Evans; Kariuki, Symon M.; Ouedraogo, Soumaila; Odhiambo, Rachel; Osuka, Daniel; Wekesa, Eliud; Kitsao-Wekulo, Patricia; Kiragga, Agnes; Kyobutungi, Catherine Abstract: Background: The Demographic and Health Surveys (DHS) Program, launched in 1984, provides high-quality population health data that underpins a vast body of global health research. However, the scale and growth patterns of DHS-based publications remain underexplored, particularly as donor funding uncertainties threaten program sustainability. Objective: We examine temporal trends in DHS-based research output from 1984 to 2025, quantifying growth patterns and publication delays to inform understanding of the program’s global research expansion. Methods: A systematic bibliometric review was conducted following PRISMA guidelines across PubMed, Scopus, Web of Science, Dimensions, Wiley, and CINAHL. Eligible peerreviewed articles using DHS data between 1984 and 2025 were identified. Annual publication counts were analyzed, segmented regression identified growth inflection points, and timeliness was assessed by calculating lag between survey completion and publication. Results: Over 10,000 DHS-based publications were identified. Annual output rose from isolated studies in the 1980s to several hundred annually by the 2010s. Segmentation analysis revealed two rapid growth phases: a 56-publications/year increase from 2004–2012, and a 71- publications/year increase from 2012 to 2024. Despite this growth, median lag from survey completion to publication remained approximately 5 years, with only a modest recent improvement (Kendall’s τ = −0.623, p < 0.001). Conclusion: DHS data have fueled exponential growth in global health research over four decades, confirming their vital role in evidence generation. However, persistent publication delays highlight the need to shorten the pathway from data collection to dissemination through strengthened research capacity in low- and middle-income countries. Sustained funding is essential to maintain this critical evidence source. Description: https://doi.org/10.1080/16549716.2026.2680363