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11.
Olusola Akinyele 《Annali di Matematica Pura ed Applicata》1979,121(1):351-372
Summary We investigate stability, uniform stability and equi-asymptotic stability with respect to the x-components and y-components
of a differential equation with time delay. We also obtain necessary and sufficient conditions for the generalized asymptotic
stability of the exponential type with respect to the components which generalizes the work of Corduneanu[3]. We make use of Lyapunov functionals and differential inequalities in our study.
Entrata in Redazione il 7 luglio 1978. 相似文献
12.
We report some new results associated with the synchronization behavior of two coupled double-well Duffing oscillators (DDOs). Some sufficient algebraic criteria for global chaos synchronization of the drive and response DDOs via linear state error feedback control are obtained by means of Lyapunov stability theory. The synchronization is achieved through a bistable state in which a periodic attractor co-exists with a chaotic attractor. Using the linear perturbation analysis, the prevalence of attractors in parameter space and the associated bifurcations are examined. Subcritical and supercritical Hopf bifurcations and abundance of Arnold tongues -- a signature of mode locking phenomenon are found. 相似文献
13.
Olusola Bodede Garland K. More Roshila Moodley Paul Steenkamp Himansu Baijnath Vinesh Maharaj Gerhard Prinsloo 《Molecules (Basel, Switzerland)》2022,27(12)
This work presents the first report on the phytochemical investigation of Harpephyllum caffrum Bernh. gum exudate. A known cardanol, 3-heptadec-12′-Z-enyl phenol (1) and three new alk(en)ylhydroxycyclohexanes, namely, (1R,3R)-1,3-dihydroxy-3-[heptadec-12′(Z)-enyl]cyclohexane (2) (1S,2S,3S,4S,5R)-1,2,3,4,5-pentahydroxy-5-[octadec-13′(Z)-enyl]cyclohexane (3) and (1R,2S,4R)-1,2,4-trihydroxy-4-[heptadec-12′(Z)-enyl]cyclohexane (4) were isolated from the gum. The structures of the compounds were determined by extensive 1D and 2D NMR spectroscopy and HR-ESI-MS data. The ethanolic extract of the gum was found to be the most potent tyrosinase inhibitor with IC50 of 11.32 µg/mL while compounds 2 and 3, with IC50 values of 24.90 and 26.99 µg/mL, respectively, were found to be potential anti-tyrosinase candidates from the gum. Gum exudate may be a potential source for non-destructive harvesting of selective pharmacologically active compounds from plants. The results also provide evidence that H. caffrum gum may find application in cosmetics as a potential anti-tyrosinase agent. 相似文献
14.
O. I. Olusola A. N. Njah S. K. Dana 《The European physical journal. Special topics》2013,222(3-4):927-937
We introduce a type of cyclic coupling to investigate synchronization of chaotic oscillators. We derive analytical solutions of the critical coupling for stable synchronization under the cyclic coupling for the Rössler system and the Lorenz oscillator as paradigmatic illustration. Based on the master stability function (MSF) approach, the analytical results on critical coupling are verified numerically. An enhancing effect in terms of lowering the critical coupling or enlarging the synchronization window in a critical coupling space is noticed. The cyclic coupling is also applied in other models, Hindmarsh-Rose model, Sprott system, Chen system and forced Duffing system to confirm the enhancing effect. The cyclic coupling allows tuning of two coupling constants in reverse directions when an optimal control of synchronization is feasible. 相似文献
15.
The increasing numbers of cases of antibiotic resistance among pathogenic bacteria such as Vibrio species poses a major problem to the food and aquaculture industries, as most antibiotics are no longer effective in controlling pathogenic bacteria affecting these industries. Therefore, this study was carried out to assess the antibacterial potentials of crude aqueous and n-hexane extracts of the husk of Cocos nucifera against some selected Vibrio species and other bacterial pathogens including those normally implicated in food and wound infections. The crude extracts were screened against forty-five strains of Vibrio pathogens and twenty-five other bacteria isolates made up of ten Gram positive and fifteen Gram negative bacteria. The aqueous extract was active against 17 of the tested bacterial and 37 of the Vibrio isolates; while the n-hexane extract showed antimicrobial activity against 21 of the test bacteria and 38 of the test Vibrio species. The minimum inhibitory concentrations (MICs) of the aqueous and n-hexane extracts against the susceptible bacteria ranged between 0.6-5.0 mg/mL and 0.3-5.0 mg/mL respectively, while the time kill study result for the aqueous extract ranged between 0.12 Log?? and 4.2 Log?? cfu/mL after 8 hours interaction in 1 x MIC and 2 x MIC. For the n-hexane extract, the log reduction ranged between 0.56 Log?? and 6.4 Log?? cfu/mL after 8 hours interaction in 1 x MIC and 2 x MIC. This study revealed the huge potential of C. nucifera extracts as alternative therapies against microbial infections. 相似文献
16.
Zholkovskiy EK Adeyinka OB Masliyah JH 《The journal of physical chemistry. B》2006,110(39):19726-19734
In the present paper, the spherical cell approach is employed for addressing the effective viscosity of suspensions of spherical particles. The proposed derivation is based on the only assumption which constitutes the essence of the spherical cell approach: a representative part of the suspension is a spherical cell which contains a particle surrounded by the continuous phase. In contrast with the previous studies on this topic, no additional assumptions are used in the present analysis. The general method of derivation and the final result, which represents the effective viscosity as a function of the solid-phase volume fraction, are compared with earlier studies where the spherical cell approach was applied for describing the effective viscosity. 相似文献
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18.
Adun Humphrey Adedeji Michael Dagbasi Mustafa Bamisile Olusola Senol Mehmet Kumar Ravinder 《Journal of Thermal Analysis and Calorimetry》2021,145(3):1413-1429
Journal of Thermal Analysis and Calorimetry - Hybrid nanofluids have been known to provide perceptibly increased heat transfer characteristics over conventional fluid, and so have been... 相似文献
19.
Oluwasola S. Oni Olusola O. Adesope Rachel Wong Krista Nishida 《School science and mathematics》2023,123(1):3-13
Concept mapping remains widely used in education. However, little is known about how self-constructed concept maps and peer feedback can improve student learning outcomes in chemistry. We investigated the effects of peer feedback on concept mapping and how it improves students' learning performance in a large second-semester, introductory chemistry course. Three hundred and twenty students were randomly assigned to one of two concept mapping conditions: self-constructed concept map with peer feedback and self-constructed concept map without peer feedback. Each group constructed concept maps that depicted the relationship between concepts on the topic of intermolecular force. The results showed that students in the self-constructed concept map with peer feedback condition outperformed students in the no peer feedback condition in chemistry learning outcome. Overall, this study demonstrates that peer feedback enhances the effectiveness of learning with generative concept maps. The implications and future directions are discussed. 相似文献