Contribution of transition and stabilization processes to speciation is a function of the
Journal ArticleCurrently the origin and trajectories of novel traits are emphasised in evolutionary studies, the role of stabilization is neglected, and interpretations are often post hoc rather than as hypothesised responses to stated agents of selection. Here we evaluated the impact of changing environmental conditions on trait evolution and stabilization and their relative contribution to diversification in a prominent Australian genus, Hakea (Proteaceae). We assembled a time-based phylogeny for Hakea, reconstructed its ancestral traits for six attributes and determined their evolutionary trajectories in response to the advent or increasing presence of fire, seasonality, aridity, nectar-feeding birds and (in)vertebrate herbivores/granivores. The ancestral Hakea arose 18 million years ago (Ma) and was broad leaved, non-spinescent, insect-pollinated, had medium-sized, serotinous fruits and resprouted after fire. Of the 190 diversification events that yielded the 82 extant species analysed, 8−50% involved evolution, stabilization or re-evolution (reversal) of individual novel traits. Needle leaves appeared 14 Ma and increased through the Neogene/Quaternary coinciding with
vertebrate herbivores. Bird-pollination appeared 14 Ma in response to advent of the Meliphagidae in the early Miocene. Small and large woody fruits evolved from 12 Ma as alternative defenses against granivory. Fire-caused death evolved 14 Ma, accounting for 50% of subsequent events, as fire became less stochastic. Loss of serotiny began in the late Miocene as non-fireprone habitats became available but only contributed 8% of events. Innovation and subsequent stabilization of functional traits promoted the overall species diversification rate in Hakea by 15 times such that only three species now retain the ancestral phenotype. Our approach holds great promise for understanding the processes responsible for speciation of organisms when the ancestral condition can be identified and the likely selective agents are understood.intensifying seasonality and aridity. Spinescence arose 12 Ma consistent with the advent of
Byron B. Lamont, Shhoob Mohamed Emhemed Elahmir, (10-2017), bioRxiv: l[gm, 1 (1), 11-20
) تحديد اصناف الزيتون المنتشرة بمنطقة ومحاولة تحديد زمن الجني لها
مقال في مجلة علمية) تحديد اصناف الزيتون المنتشرة بمنطقة ومحاولة تحديد زمن الجني لها
خليفة سليمان محمد زنين، عمر علي سعيد مفتاح، اشهوب محمد أمحمد الأحمر، (02-2017)، غريان: مجلة جامعة غريان، 17 (1)، 155-165
The Impact of Water and Some Salt Solutions on Some Properties of Hydrophilic Acrylamide Copolymeric Hydrogels
Journal ArticleA series of polyelectrolyte hydrogels ranging from 92-98wt% were synthesized by copolymerization of acrylamide,
AAM with 2-acrylamido-2-methyl propane sulphonic acid, AMPS using 0.001g APS as initiator in the presence of 30wt% H2O
and 1.0wt% ethylene glycol dimethacrylate,EDMA as cross-linking agent. The final copolymers was obtained in the form of
glassy and transparent roads at room temperature, these roads were soaked in water for two days to remove unreacted
monomers. The swelling behavior of the hydrogels was studied in distilled water and salt solutions of 1.5 mol/l each of NaCl
and KCl. The Swelling in water shows decreasing values of q, LE, Ø1, EWC% and increasing polymer volume fraction, Ø2 by
increasing acrylamide, due to increasing hydrophobicity and decreasing the hydrophilicity. The swelling in salt solutions
shows a decreasing in the values of ESSNa%, WCNa%, SCNa%, ESSK%, WCK% and SCK% by increasing acrylamid
monomer in the feed due to increasing the hydrophobicity and decreasing the ionized ionic groups (SO3H). The increasing
values of ESSNa%, WCNa% and SCNa% compared with the values of ESSK%, WCK% and SCK% respectively, is due to
the higher charge density of sodium ion than that of potassium ion.
Abdurhman A.Abuabdalla, Shhoob Mohamed Emhemed Elahmir, (01-2017), MAYFEB: MAYFEB Journal of Materials Science, 1 (1), 7-16
Temperature effect on sorption capacity of PP melt electrospun ultrafine fibers in marine oil spill clean up
Journal ArticleMarine Oil spills have become a serious environmental problem, and contribute to severe impacts and economic losses. Fast and efficient cleanup of oil from marine environment is vital. The use of sorbents is one of the most efficient techniques in removing oil from water. In this work, pure polypropylene (PP) ultrafine fibers with 2 μm diameter were prepared by air assisted melt electrospinning device to be used as oil sorbent. Two fiber samples were used in this study, fluffy, cotton like appearance and oriented, cloth like appearance with different porosities. The influence of temperature change on oil/water mixture was studied. Fluffy fibers showed a better performance in sorption capacity. Results indicated that change in temperature was an important factor in determining the sorption capacity of the fibers. Additionally, in contrast to solution electrospinning, melt electrospinning is safer, cost effective and …
Mahmoud M Bubakir, (01-2017), Key Engineering Materials: Trans Tech Publications Ltd, 0 (717), 104-111
Small-seeded Hakea species tolerate cotyledon loss better than large-seeded congeners
Journal ArticleSix Hakea species varying greatly in seed size were selected for cotyledon damage experiments. The
growth of seedlings with cotyledons partially or completely removed was monitored over 90 days. All
seedlings perished by the fifth week when both cotyledons were removed irrespective of seed size.
Partial removal of cotyledons caused a significant delay in the emergence of the first leaf, and reduction
in root and shoot growth of the large-seeded species. The growth of seedlings of small-seeded species
was less impacted by cotyledon damage. The rate of survival, root and shoot lengths and dry biomass
of the seedlings were determined after 90 days. When seedlings were treated with balanced nutrient
solutions following removal of the cotyledons, survival was 95–98%, but 0% when supplied with
nutrient solutions lacking N or P or with water only. The addition of a balanced nutrient solution failed
to restore complete growth of any species, but the rate of root elongation for the small-seeded species
was maintained. Cotyledons provide nutrients to support early growth of Hakea seedlings, but other
physiological roles for the cotyledons are also implicated. In conclusion, small-seeded Hakea species can
tolerate cotyledons loss better than large-seeded species..
Shhoob Mohamed Emhemed Elahmir, (12-2016), Scientific Reports: Springer International Publishing, 10 (1), 1-9
PLOS ONE
Journal ArticleSeed size is a key functional trait that affects plant fitness at the seedling stage and may vary greatly with species fruit size, growth form and fecundity. Using structural equation modelling (SEM) and correlated trait evolution analysis, we investigated the interaction network between seed size and fecundity, postfire regeneration strategy, fruit size, plant height and serotiny (on-plant seed storage) among 82 species of the woody shrub genus, Hakea, with a wide spectrum of seed sizes (2–500 mg). Seed size is negatively correlated with fecundity, while fire-killed species (nonsprouters) produce more seeds than resprouters though they are of similar size. Seed size is unrelated to plant height and level of serotiny while it scales allometrically with fruit size. A strong phylogenetic signal in seed size revealed phylogenetic constraints on seed size variation in Hakea. Our analyses suggest a causal relationship between seed size, fecundity and postfire regeneration strategy in Hakea. These results demonstrate that fruit size, fecundity and evolutionary history have had most control over seed size variation among Hakea species
Shhoob Mohamed Emhemed Elahmir, (06-2015), PLOS ONE: مجلة plos one, 10 (3), 1-12
Water filtration properties of novel composite membranes combining solution electrospinning and needleless melt electrospinning methods
Journal ArticleNew composite polyvinyl alcohol (PVA)/polypropylene (PP) membranes were prepared by combining both solution electrospinning and melt electrospinning methods. Self‐designed and made needleless melt electrospinning device was used to fabricate PP membranes which acted as the support layer. PVA membrane on the surface was fabricated via solution electrospinning. The electrospun PVA/PP composite membranes were characterized by the pore size distribution, pure water flux, and rejection ratio, then compared with general composite membranes. Characterizations revealed that the fiber diameter of solution electrospun PVA membrane and melt electrospun PP membrane were 0.171 ± 0.027 and 2.24 ± 0.33 μm, respectively, and the average pore size was 0.832 μm and 27.29 μm, which was much smaller than the nonwoven membrane. The rejection ratio to the 500 nm particles of the PVA/PP …
Mahmoud M Bubakir, (03-2015), Journal of Applied Polymer Science: Wiley Periodicals, Inc, 10 (132),
Mass production of ultra-fine fibre by melt electrospinning method using umbellate spinneret
Journal ArticleSolventless melt electrospinning which allows mass production is substantially safe. It can produce fibres of hundreds of nanometres, one order of magnitude lower than that of conventional melt-blown spinning. In this paper, a comparison between different technologies producing ultra-fine fibre reveals the advancement of melt electrospinning method using umbellate spinneret for ultra-fine fibre mass production. Some typical industrial polymer materials was also spun using melt electrospinng method, including biodegradable materials like polylactic acid and polycaprolactone (PCL), which may contribute to some interesting applications. In addition, a machine for mass production is also proposed. Finally, proposition of the industrialisation of ultra-fine fibre by melt electrospinning is discussed.
MM Bubakir, (07-2014), Materials Research Innovations: Taylor & Francis, 4 (18), 921-925
Polypropylene fibers fabricated via a needleless melt‐electrospinning device for marine oil‐spill cleanup
Journal ArticleUltrafine polypropylene (PP) fibers as oil sorbents were fabricated via a needleless melt‐electrospinning device and were characterized by scanning electron microscopy and contact‐angle analysis. PP fibers of various diameters and porosities were obtained by the manipulation of the applied electrical field. The effects of the fiber diameter and porosity on the oil‐sorption capacity and oil‐retention behavior were investigated. The experimental results demonstrate that for fiber diameter on the microscale, the porosity played a paramount role in determining the oil‐sorption capacities. The maximum oil‐sorption capacity of the resulting PP fibers with regard to motor oil and peanut oil were 129 and 80 g/g, respectively; these values were approximately six to seven times that of commercial PP nonwoven fabricated through the melt‐blown method. In addition, even after seven sorption/desorption cycles, the oil‐sorption
Mahmoud M Bubakir, (05-2014), Journal of Applied Polymer Science: Wiley Periodicals, Inc, 7 (131),
Study of Melt Differential Electrospinning Process and the Porosity of Electrospun Polypropylene Composite Fibers
Journal ArticleIn this study, polypropylene was mixed with three different pore-forming agents (nanometer cal-cium carbonate, paraffin and inorganic hybrid salts) to form three blended systems which were used to pro-duce composite fibers by self-made melt differential electrospinning device. Polypropylene fibers withrough surface and microporous were prepared after removing above-mentioned pore-forming agents. Thesurface morphological structures of these polypropylene fibers were characterized. Results showed that theaverage diameter of polypropylene-nanometer calcium carbonate composite fibers (8.22 μm), polypropylene-paraffin composite fibers (8.67 μm) and polypropylene-inorganic hybrid salts composites fiber (6.08 μm) wasless than pure polypropylene fibers (12.10 μm); the diameter of composite fibers was not reduced with theincreasing of melt index; polypropylene fibers without nanometer calcium carbonate comprised microporoushaving different sizes and uneven distribution, polypropylene fibers without paraffin had rough surface andstrip or bulk dents, polypropylene fibers without inorganic hybrid salts comprised microporous having rela-tively small sizes and even distribution. These three polypropylene fibers were all able to increase the hydro-philicity or hydrophobicity of materials. Furthermore, the number of Taylor cone was increased by using as-sistant air flow. Taylor cone contributed to the stability of jet flow and the refining of composite fibers whenTaylor cone increased to a certain number.
Mahmoud Bubakir, (01-2014), Synthetic Fiber in China: Synthetic Fiber in China, 1 (1), 1-1