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Articles by N.A. Obasi
Total Records ( 5 ) for N.A. Obasi
  N.A. Obasi , E.I. Akubugwo , O.C. Ugbogu and Glory Otuchristian
  Physico-chemical parameters (pH, EC, %moisture, CEC, TOC, TOM, total nitrogen, %PO43¯, SO42¯) and the chemical fractionation, mobility and bioavailability of heavy metals (Cd, Cu, Mn, Pb, Zn, Fe, Ni and Cr) in refuse waste soils of some dumpsites along Enugu-port Harcourt Expressways, South-East, Nigeria were investigated and compared with control soils from the same terrain using standard analytical methods. Results showed significant (p>0.05) higher changes in the soil physico-chemical properties relative to the controls, thus implicating the waste soils to be more fertile. Also, mean of total extractable metals in the samples analyzed for Cd, Cu, Mn, Pb, Zn, Fe, Ni and Cr ranged from 23.41-107.18, 10.58-238.50, 141.21-442.03, 35.11-635.31, 186.38-505.57, 76.46-371.73, 13.00-221.97 and 13.55-26.77 mg kg-1 dry weight, respectively. Cd followed by Fe and then Pb were mostly found to be in the mobile phase of the samples indicating that the metals were potentially more bio-available to the environment than the other metals studied. Overall, the order of mobility and bioavailability of the metals is Cd>Fe>Pb>Mn>Zn>Cr>Ni>Cu. The implications of these results towards the understanding of the underlying causes of plants species diversity changes and growth, bioaccumulation and bio-toxicity of some edible plants on dumpsites were discussed.
  N.A. Obasi , U.C. Okorie , B.N. Enemchukwu , S.S. Ogundapo and G. Otuchristian
  The numerous ethno-medicinal applications of Picralima nitida plants have called for a high thorough-put investigation of all the parts of the plant including the peel that is usually discarded in order to ensure maximum utilization of the plant. In this study, nutritional evaluation, phytochemical screening and antimicrobial effects of Picralima nitida peel were carried out using standard methods, in order to determine the potentials of this discarded part of the plant. The results of proximate contents indicated the following: moisture (49.6%), ash (16.0%), crude fibre (10.5%), crude lipid (7.4%), crude protein (28.4%) and carbohydrate (37.7%) while its calorific value is 265.8 kcal/100 g. Thus, the nutritional value of Picralima nitida peel is high and as such it could be used as feed additives. The results of phytochemical screening revealed the presence of flavonoids, saponins, tannins and alkaloids and the aqueous extract had antimicrobial activities against Escherichia coli and staphylococcus aureus with varying degrees. The most potent inhibitory effect was observed with Escherichia coli. These results have revealed that the peel and its extracts have pharmacological active compounds and antibacterial effects and as such could be used in ethno-medicine for the treatment of microbial infection and other ailments.
  A.I. Ezeribe , C.J. Chukwu , N.A. Obasi , G. Otuchristian and U.A. Ibiam
  Synthesis of mono through hexa substituted derivatives of Methylol Melamine Resins (MFR) were carried out at various catalyst (KH2PO4) concentrations of 0.5, 0.75, 1.0, 1.25 and 1.50 g. Rheological/mechanical properties of resin-cotton network were investigated to determine the effect of catalyst concentration and degree of substitution of resins on the flow property such as viscosity. Other parameters determined include percentage yield, breaking load and crease recovery properties of resinated cotton fabric. The result revealed that the yield increased with increase in catalyst concentration and attained the highest yield of 53.7% at 0.75 g and 51.3% at 1.0 g, respectively. The damaging effects of high acid concentrations were observed particularly at 1.25 and 1.50 g KH2PO4. Yield increased as the degree of substitution increased with hexa substitution having 48.8 and 53.7% at 0.5 and 0.75 g, respectively. Shear viscosity increased as catalyst concentration increased from 0.5 to 1.0 g with hexa and penta substitution giving the highest shear viscosity of 45 poises and 35 poises, respectively. The dry crease recovery angle increased with increased catalyst concentration up to 0.75 g and attained maximum value of 125° and 115° in the warp and weft directions, respectively at 150°C. The effect of catalyst on breaking load of sample at 150°C showed an increase from 0.5-1.0 g of catalyst concentration. The highest tear strength of 10.8 and 10.2 kgf at 0.75 g catalyst concentration was observed in the warp and weft directions, respectively. Acid damage at higher concentration was also implicated for the reduced tear strength.
  K.M. Kalu , N.A. Obasi , F.O. Nduka and E.I. Okonkwo
  Transmission of human malaria requires contacts between vectors of malaria, Anopheles spp. and human hosts. In the present study, the abundance of nocturnal and endophagous anthropophagous anophelines species in Umuchieze and Uturu, rural communities in Abia State, Southeast, Nigeria, was investigated using “all-night human-bait indoor insecticide spray sheet catches” method for two consecutive years. Catch was made once a week in each community. A total of 500 adult mosquitoes (all female anophelines) was captured, 170 (34.00%) in Umuchieze Community and 330 (66.00%) in Uturu. Three Anopheles species: Anopheles gambiae, Anopheles funestus and Anopheles moucheti were found in the studied communities except in Umuchieze Community where Anopheles moucheti was never caught. Anopheles gambiae was dominant in both study communities with the species relative abundance of 55.29 and 51.82% recorded in Umuchieze and Uturu Communities, respectively. The relative abundances of various prevalent Anopheles species were higher during rainy season than the dry season. This periodic occurrence of the important malaria vectors explains periodicity of malaria epidemiology in the study communities. The high abundance rates of nocturnal and endophagous anthropophagous anophelines recorded in the two communities predispose inhabitants of the areas to incessant contact with the human malaria vectors resulting in the study areas being malaria endemic.
  N.A. Obasi , Joy Ukadilonu , Eberechukwu Eze , E.I. Akubugwo and U.C. Okorie
  Proximate composition, extraction, characterization and comparative assessment of Cocos nucifera and Colocynthis citrullus seeds and seed oils were evaluated in this work using standard analytical techniques. The results showed the percentage (%) moisture, crude fibre, ash, crude protein, lipids and total carbohydrate contents of the seeds as 7.51 and 4.27, 7.70 and 5.51, 1.02 and 2.94, 10.57 and 11.67, 47.80 and 50.42 and 32.84 and 29.47 while the calorific values were 553.99 and 567.32 Kcal/100 g for C. nucifera and C. citrullus, respectively. The two seed oils were odourless and at room temperature (30°C) liquids, with a pale yellow to yellowish colouration. Lipid indices of the seed oils indicated the Acid Values (AV) as 2.06-6.36 mg NaOH g-1 and 2.99-6.17 mg NaOH g-1, Free Fatty Acids (FFA) as 1.03-3.18 and 1.49-3.09%, Saponification Values (SV) as 252.44-257.59 and 196.82-201.03 mg KOH g-1, Iodine Values (IV) as 9.73-10.99 and 110.93-111.46 mg of I2 g-1 of oil and Peroxide Values (PV) as 0.21-0.21 and 1.53-2.72 mg O2 kg-1 for soxhlet-mechanical extracted C. nucifera and C. citrullus seed oils, respectively. The studied characteristics of the oil extracts in most cases compared favourably with most conventional vegetable oils sold in the Nigeria markets; however, there were some observed levels of significant differences in the values at p≤0.05. These results suggest that the seeds examined may be nutritionally potent and also viable sources of seed oils judging by their oil yield. The data also showed that the seed oils were edible inferring from their low AV and their corresponding low FFA contents. Industrially, the results revealed the seed oils to have great potentials in soap manufacturing industries because of their high SV. They were also shown to be non-drying due to their low IV which also suggested that the oils contain few unsaturated bonds and therefore have low susceptibility to oxidative rancidity and deterioration as confirmed by their low PV which also serves as indicators of the presence or high levels of anti-oxidants in the oils.
 
 
 
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