https://repository.seku.ac.ke/handle/123456789/19 Sat, 11 Apr 2026 14:52:52 GMT 2026-04-11T14:52:52Z https://repository.seku.ac.ke/handle/123456789/8337 Phylogeographic perspectives on conserving the endangered monotypic genus acanthochlamys (Velloziaceae) Wakhungu, Dennis A.; Li, Zhi-Peng; Kipkoech, Amos; Wambulwa, Moses C.; Oyebanji, Oyetola O.; Milne, Richard I.; Dudley, Christopher; Mambo, Winnie W.; Xu, Bo; Liu, Jie The accelerating loss of global biodiversity necessitates proactive conservation strategies that integrate genetic diversity with projected climate impacts, especially in biodiversity hotspots such as the Hengduan Mountains. While previous phylogeographic studies in this region primarily relied on a few DNA fragments, plastid phylogeography has seldom been integrated with ecological niche modelling for conservation planning. Here, we combined plastid phylogeography and ecological niche modelling using data from 107 individuals across 14 populations of Acanthochlamys bracteata, a vulnerable alpine species and monotypic genus, to identify genetically distinct populations and predict potential climatic refugia. We identified three genetically distinct groups (Groups A to C), all characterised by low nucleotide diversity but high haplotype endemism. Notably, Group C comprised a single population from Luhuo County, Sichuan Province, and represents an independent evolutionarily significant unit due to its pronounced genetic distinctiveness. Most genetic variation occurred among populations, with one population showing relatively high diversity, while three lacked variation. A northward range shift and expansion of suitable habitats are projected under future climatic scenarios. Three climatic refugia were identified, characterized by divergent genetic lineages and numerous private haplotypes, and supported by the persistence of suitable habitat through time. The observed phylogeographic structure is likely driven by both geographical distance and relict persistence. We recommend that conservation efforts should focus on protecting genetically distinct and diverse populations through an integration of in situ, ex situ, and assisted migration measures. This study advances our understanding of the evolutionary history of Acanthochlamys bracteata and could serve as a model for conserving other rare and isolated plants under climate change and human disturbance. https://doi.org/10.1007/s12686-026-01423-y Mon, 06 Apr 2026 00:00:00 GMT https://repository.seku.ac.ke/handle/123456789/8337 2026-04-06T00:00:00Z https://repository.seku.ac.ke/handle/123456789/8335 Investigation of rejuvenation and modification of aged asphalt binders by using aromatic oil-SBS polymer blend Hong, Wei; Mo, Liantong; Pan, Changluan; Riara, Martin M.; Wei, Mi; Zhang, Jizhe In this paper, long-term aged base asphalt and SBS modified asphalt binders were rejuvenated and modified simultaneously using a compound rejuvenator containing 77% aromatic oil and 23% SBS polymer. Aromatic oil was used for rejuvenation purpose due to its softening effect while SBS polymer was used for modification purpose because of its potential to form a polymer network. Conventional bitumen tests, dynamic shear rheological (DSR) test and bending beam rheological (BBR) test were conducted to evaluate the rejuvenation and modification effects. Test results indicated that use of the compound rejuvenator enhanced the softening point and ductility for both aged base asphalt and SBS modified asphalt binders. The polymer modification effect of compound rejuvenator was well distinguished by the plateau region of phase angle master curves. Aromatic oil had a strong softening effect on aged asphalt binder which improved the performance at low temperatures, but weakened the performance at high temperatures. The incorporation of SBS polymer was a good supplement to balance the overall performance of rejuvenated asphalt binders. The compound rejuvenator can be greatly effective for hot recycling of reclaimed asphalt mixture by means of the simultaneous rejuvenation and modification. https://doi.org/10.1016/j.conbuildmat.2019.117154 Mon, 20 Jan 2020 00:00:00 GMT https://repository.seku.ac.ke/handle/123456789/8335 2020-01-20T00:00:00Z https://repository.seku.ac.ke/handle/123456789/8328 Localized surface plasmon resonance and damping mechanisms in transition metals Sila, Faith; Mbaluka, Benjamin; Riara, Martin M.; Katumo, Ngei This work reports the calculated dependence of the localized surface plasmon resonance (LSPR) parameters and damping mechanism on nanoparticle size of unconventional transition metals, including zinc, silver, rhodium, rhenium, molybdenum, tantalum, titanium, and scandium, within the size range of 10 to 400 nm. The study applies Mie theory to determine the peak energies, amplitude, and full width at half maximum (FWHM) of LSPR as a function of size, shape, and material type. We have found that the parameters of LSPR depend on electron structure and damping mechanisms. LSPR amplitude decreased systematically for individual nanoparticles (NPs) for sizes 10…200 nm, after which, a similar trend was exhibited due to radiative damping. Au, Sc and Ag are the only metal NPs that exhibited a significant FWHM of LSPR at sizes approximately below 40 nm. For all investigated transition metal NPs, smaller NPs exhibited higher absorption and lower scattering, while larger NPs showed narrower FWHM and red-shifted LSPR peaks due to retardation effects and multipolar plasmon excitations. The analysis highlights that some transition metal NPs exhibit optical characteristics similar to those of gold, silver, and copper, making them a good alternative for the mentioned ones at specific NP sizes. DOI: https://doi.org/10.15407/spqeo29.01.051 Mon, 23 Mar 2026 00:00:00 GMT https://repository.seku.ac.ke/handle/123456789/8328 2026-03-23T00:00:00Z https://repository.seku.ac.ke/handle/123456789/8326 Genetic analysis of walnut cultivars from southwest China: Implications for germplasm improvement Wambulwa, Moses C.; Fan, Peng-Zhen; Milne, Richard; Wu, Zeng-Yuan; Luo, Ya-Huang; Wang, Yue-Hua; Gao, Lian-Ming; Xiahou, Zuo-Ying; Jin, Ye-Chuan; Ye, Lin-Jiang; Xu, Zu-Chang; Yang, Zhi-Chun; Li, De-Zhu; Liu, Jie Walnuts are highly valued for their rich nutritional profile and wide medicinal applications. This demand has led to the intensification of breeding activities in major walnut production areas such as southwest China, in order to develop more superior cultivars. With the increasing number of cultivars, accurate identification becomes fundamental to selecting the right cultivar for grafting, industrial processing or development of new cultivars. To ensure proper identification of cultivars and understand the genetic structure of wild and cultivated material, we genotyped 362 cultivated and wild individuals of walnut trees from southwest China (with two additional populations from Xinjiang, plus three cultivars from Canada, France and Belgium) using 36 polymorphic microsatellite loci. We found relatively low indices of genetic diversity (HO = 0.570, HE = 0.404, NA = 2.345) as well as a high level of clonality (>85% of cultivars), indicating reliance on genetically narrow sources of parental material for breeding. Our STRUCTURE and PCoA analyses generally delineated the two species, though considerable levels of introgression were also evident. More significantly, we detected a distinct genetic group of cultivated Juglans sigillata, which mainly comprised individuals of the popular ‘Yangbidapao’ landrace. Finally, a core set of 18 SSR loci was selected, which was capable of identifying 32 cultivars. In a nutshell, our results call for more utilization of genetically disparate material, including wild walnut trees, as parental sources to breed for more cultivars. The data reported herein will significantly contribute towards the genetic improvement and conservation of the walnut germplasm in southwest China. https://doi.org/10.1016/j.pld.2021.08.005 Tue, 01 Nov 2022 00:00:00 GMT https://repository.seku.ac.ke/handle/123456789/8326 2022-11-01T00:00:00Z