Antifungal properties of Musa paradisiaca (Plantain) peel and stalk extracts

Effect of plantain (Musa paradisiaca (L) AAB genomic group) peel and stalk extracts were investigated using percentage inhibition test. Complete inhibition of growth (100%) was observed for Aspergillusniger, Aspergillus oryzae and Rhizopus stolonifer at 1.0 mg/ml concentration of stalk extract. Peel extract inhibited A. niger 100%, A. oryzae 76.67% and R. stolonifer 56.67% at the same concentration. As concentration reduces, growth inhibition reduces also up to the minimum inhibitory concentration. The results of this work justify that the plant extracts were able to inhibit and kill the growth of spoilage fungi and this implies that the extract inappropriate doses can be used in food preservation and to treat infections caused by this spoilage fungi. The results further justify the claim that Musa paradisiaca (L) stalk and peel extract demonstrated antifungal actionin which methanol was seen to be a better solvent for extracting active ingredients from medicinal plants considering the high susceptibility of test organisms to methanol extract than ethanol extract used in this study.Phytochemical screening showed the presence of hydrogen cyanide, tannin, alkaloid, steroid, saponin and flavonoid. The growth inhibition of A. niger, A. oryzae and R. stolonifer by Musa paradisiaca peel and stalk methanol and ethanol extract in this study suggest the presence of antifungal substance in the plant tissue and the possibility of using the extract to control plant pathogens especially where the spoilage fungi used in thisstudy are involved

Comparative Study of Pre-Germination Treatments and their Effects on the Growth of Tectona Grandis (Linn. F) Seedlings

A comparative study was conducted for three months to investigate the effect of pre-germination treatment on morphological and physiologicalcharacteristics of Tectona grandis (Linn. F) seedlings. Matured seeds of Tectona grandis were collected from mother trees in Uyo and exposed to four pre-germination treatments – soaking in running water (SRW) for 24 hours, soaking in stagnant water (SSW) for 24 hours, soaking in boiled water (SBW) for 5 minutes and no treatment as control. Treated seeds were sown in the of Forestry and Wildlife Department nursery, University of Uyo by broadcast method in germination boxes. At two-leaf stage, fairly uniformed seedlings from each treatment were selected and transplanted into polypots filled with topsoil and laid on the field in completely randomized design, replicated three times. Morphological and physiological features were assessed after two weeks of transplanting and fortnightly thereafter. Data were subjected to ANOVA and the significant means separated using F-LSD. The result showed that pre-germination treatment had significant effect (p>0.05) on seedling height, number of leaves, stem collar diameter and biomass production while there was no significant effect (

Magnetic vortex oscillator driven by dc spin-polarized current

Transfer of angular momentum from a spin-polarized current to a ferromagnet provides an efficient means to control the dynamics of nanomagnets. A peculiar consequence of this spin-torque, the ability to induce persistent oscillations of a nanomagnet by applying a dc current, has previously been reported only for spatially uniform nanomagnets. Here we demonstrate that a quintessentially nonuniform magnetic structure, a magnetic vortex, isolated within a nanoscale spin valve structure, can be excited into persistent microwave-frequency oscillations by a spin-polarized dc current. Comparison to micromagnetic simulations leads to identification of the oscillations with a precession of the vortex core. The oscillations, which can be obtained in essentially zero magnetic field, exhibit linewidths that can be narrower than 300 kHz, making these highly compact spin-torque vortex oscillator devices potential candidates for microwave signal-processing applications, and a powerful new tool for fundamental studies of vortex dynamics in magnetic nanostructures.Comment: 14 pages, 4 figure