| 1 | Onuegbu G. C. & Onuoha C. (2017). | Transport Behaviour of Xylene through Compatibilized Low Density Polyethylene Composite | The transport behaviour of xylene through compatibilized low density polyethylene (LDPE) composite was investigated at different temperatures 40 0C, 60 0C and 80 0C. the cola nut used was ground to 25 µm particle size. In preparation of the composite, 0 - 5 wt% cola nut powder 0 – 2.5 wt% of the compatibilizer were thoroughly mixed 200 g of low density polyethylene in an injection moulding machine. The injected LDPE/Kola nut composites were taken for sorption test. The sorption data obtained for the composites at different temperatures investigated were expressed as the mole percentage uptake, Qt (mole %). Results showed that the mole percent uptake of xylene at the five filler contents (0 – 5 wt%) generally increased with increase in sorption temperature but decreased with increase in compatibilizer and filler content. This can be seen at 80 0C and 0, 1, 1.5and 2.5 wt% of the compatibilizer respectively. The molar percentage uptake of xylene at 1 wt% of the filler yielded the following values: 8.7876, 8.5962, 8.4056 and 8.3111 respectively. At 2 wt%, it yielded 7.9812, 7.9104, 7.7423 and 7.7199 respectively; at 3 wt%, it gave 7.8232, 7.6351, 7.5663 and 7.4652; at 4 wt%, it yielded 8.4120, 8.3315, 8.2132 and 7.9667 respectively and at 5 wt%, it gave 7.9635, 7.8630, 7.6256 and 7.5013 respectively. Key words: sorption, kola nut, polyethylene, composite, xylene. | European Journal of Engineering and Technology (EJET) | Vol. 5, N0. 3
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| 2 | Onuoha C., Onyemaobi O., Anyakwo C. and Onuegbu G. (2017). | Morphology and Physical Properties of Recycled Polypropylene-Corn Cob Powder Composites | This study investigates the morphological and physical/end-use properties of corn cob powder-filled recycled polypropylene composites. The composites were prepared by incorporating corn cob powder of particle sizes 150 μm, 300 μm and 425 μm respectively at filler loadings of 5 to 25 wt%. The properties were determined according to standard test procedures. Results showed that the incorporation of corn cob powder as filler resulted to enhancement of water absorption and solvent sorption, which were found to increase with both increase in filler loading and increase in filler particle size, probably due to the hydrophilic nature of corn cob powder. It was also discovered that solvent sorption was most pronounced with benzene, followed by toluene and lastly xylene, in accordance with the relative proximity of their solubility parameters to that of polypropylene. Flame propagation rate was also found to improve by the incorporation of corn cob powder due to its high content of cellulose, a combustible organic matter. However, specific gravities of the composites were found to be lower than for the unfilled polypropylene, an implication that the composites produced are lighter in weight than the unfilled. Specific gravity increased with increase in filler loading but decreased with increase in particle size. The Morphological studies showed increase in the number of spherulites with increase in filler loading and increase in the size of the spherulites with increase in particle size. Further observation showed that the particle sizes and pores sizes detected increased with increase in filler particle size probably due to poor interaction and distribution of coarse particles. It is hoped that this present study will to help place the usefulness of corn cob as filler in the development of thermoplastic composites in future and develop its niche in the scientific record. Keywords: Recycled Polypropylene, Morphology, Physical Properties, Composites, Corn Cob, Spherulites | International Journal of Engineering and Technologies (IJET) | Vol. 11.
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| 3 | Onuoha C., Onyemaobi O. O., Anyakwo C. N. and Onuegbu G. C. (2017). | Physical and Morphological Properties of Periwinkle Shell-Filled Recycled Polypropylene Composites | Physical and morphological properties of periwinkle shell-filled recycled polypropylene composites were studied. Periwinkle shells used in this study were processed and sieved to three particle sizes of 150, 300 and 425 µm respectively. Filler loadings of 0 to 25 wt% were used in compounding the composites in an injection moulding machine and the resulting composites were extruded as sheets. Some physical and morphological properties were determined. Results showed that the incorporation of periwinkle shell powder into the recycled polypropylene matrix increased the specific gravity of the composites. Increase in filler loading resulted to increase in specific gravity probably due to enhanced dispersion of fillers. However, increase in filler particle size led to decreased specific gravity due to poor filler dispersion and consequent filler agglomeration. Water sorption was found to increase with increase in both filler loading and filler particle size due to the hydrophilic nature of the filler and enhanced porosity created by large particles. Flame propagation was found to decrease with increase in both filler loading and filler particle size due to the evolution of CO2 in the combustion process, which suppresses the burning rate. There was increase in solvent sorption with increase in both filler loading and filler particle size. It was also noticed that solvent sorption was most pronounced in benzene, followed by toluene and lastly xylene. This is in accordance with the order of closeness of their solubility parameters with that of polypropylene. Morphological analysis revealed enhanced spherulization and dispersion with smaller particle sizes but enlarged spherulization and consequent agglomeration at larger particles sizes. Based on these results, periwinkle shell can be considered suitable for the production of recycled polypropylene composites. Key Words: Physical Properties, Recycled Polypropylene, Morphology, Periwinkle Shell, Specific Gravity, Flame Propagation, Solvent Sorption. | International Journal of Innovative Science, Engineering and Technology (IJISET) | Vol. 4, Issue 5
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| 4 | Onuoha C., Onyemaobi O. O, Anyakwo C. N. and Onuegbu G. C. (2017). | Effect of Filler Loading and Particle Size on the Mechanical Properties of Periwinkle Shell-Filled Recycled Polypropylene Composites | Mechanical properties of composites of recycled polypropylene filled with periwinkle shell powder were investigated. Periwinkle shells used in this study were thoroughly cleaned, ground and sieved to three particle sizes of 150, 300 and 425 µm respectively. Filler loadings of 0 to 25 wt% were used in compounding the composites in an injection moulding machine and the resulting composites were extruded as sheets. Some mechanical properties were determined. Results showed that periwinkle shell powder improved the tensile strength, flexural strength, tensile modulus and hardness of polypropylene composites. These properties were found to increase with filler loading up to 15 wt% or 20 wt% loading (optimal filler loading) but decrease with filler particle size. However, elongation at break was found to decrease with increasing filler loading. Highest tensile and flexural strengths were obtained at 15 and 20 wt% respectively at 150 µm particle size. It is therefore concluded that periwinkle shell powder is suitable for the production of polypropylene composites.Key words: Polypropylene, periwinkle shell powder, filler, composite, particle size. | American Journal of Engineering Research (AJER) | Vol. 6, Issue 4
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| 5 | Onuoha C., Onyemaobi O. O., Anyakwo C. N. and Onuegbu G. C. (2017). | Effect of Filler Content and Particle Size on the Mechanical Properties of Corn Cob Powder Filled Recycled Polypropylene Composites | Composites of recycled polypropylene filled with corn cob powder were investigated for mechanical properties. The corn cobs were thoroughly cleaned, ground and sieved to three particle sizes of 150, 300 and 425 µm respectively. Filler loadings of 0 to 25 wt% were used in compounding the composites in an injection moulding machine and the resulting composites were extruded as sheets. Some mechanical properties such as tensile strength, flexural strength, yield strength, tensile modulus, elongation at break and hardness were determined. Results showed that incorporation of corn cob powder into the polymer matrix improved the tensile strength but had no significant improvement on flexural strength, tensile modulus and hardness of polypropylene composites. These properties were found to increase with filler loading but decrease with filler particle size. However, elongation at break was found to decrease with increasing filler loading. Highest tensile and flexural strengths were obtained at 15 and 20 wt% respectively at 150 µm particle size. It is therefore recommended that corn cob powder be used as filler in polypropylene.Keywords: Polypropylene, recycled polypropylene, corn cob, filler, composite, particle size. | International Journal of Scientific Engineering and Applied Science(IJSEAS) | Vol. 3, Issue 4
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| 6 | Ovri J.E.O., and Onuoha C. (2015). | Characterization of Some Local Nigerian Clays for Electrical Porcelain Application | Clays from Ibere and Awo-omama were characterized for electrical porcelain application. Test samples were made by varying the compositions of feldspar and quartz required to form mouldable plastic bodies with each clay. The following properties were determined: electrical resistivity, apparent porosity, water absorption and linear shrinkage. This characterization was carried out for both the locally made porcelains and the Power Holding Company of Nigeria (PHCN) (standard) porcelain. Results obtained showed that, for both clays, apparent porosity, water absorption and electrical resistivity increased with increase in the composition of the non-plastic materials (feldspar and quartz) while linear shrinkage decrease with increase in non-plastic materials. Also, for both clays, samples containing 50-70% clays, 20-30% feldspar and 10-20% quartz were found to yield results that compared well with results found in the literature as well as results obtained for PHCN (Standard) porcelain. It is therefore concluded that both clays are suitable for electrical porcelain application. Keywords: Porcelain, Characterization, Clay, Feldspar, Quartz, Electrical Resistivity | International Journal of Advanced Materials Research (IJAMR) | Vol. 1, N0. 3.
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| 7 | C. Onuoha,, J.E.O. Ovri, and U. Mark. (2014) | Characterization of Ibere Clay for the Production of Porcelain Pin Insulators | The characterization of Ibere clay for the production of porcelain pin insulators was carried out for both the locally made porcelains and the standard. Test samples were made by varying the compositions of feldspar and quartz needed to form a mouldable plastic body with the clay. The following properties were determined: electrical resistivity, apparent porosity, water absorption, bulk density and linear shrinkage. Results obtained showed that apparent porosity, water absorption and electrical resistivity increased with increase in the composition of the non-plastic materials (feldspar and quartz) while bulk density and linear shrinkage decreased with increase in non-plastic materials. The chemical composition of the clay (43.94%SiO2, 26.54%Al2O3) compares well with previous works (40-60%Si2O, 25-45%Al2O3) for the production of ceramic refractories. Linear shrinkage (8.33-9.68%), apparent porosity (10.81-17.30%) and water absorption (5.41-10.84%) are in conformity with standards (7-10%, 16.45% and 8.20% respectively). Electrical resistivities recorded (0.79-1.39 x 107Ω-m) are in agreement with results obtained for standard (0.45 x 107Ω-m). These results are obtained in samples containing 50-70% clay, 20-30% feldspar and 10-20% quartz. It is therefore concluded that imported porcelains used by Power Holding Company of Nigeria (PHCN) can be replaced with porcelains made from Ibere clay. KEY WORDS: Characterization, porcelain, clay, feldspar, quartz, porosity, electrical resistivity. | International Research Journal in Engineering, Science and Technology (IREJEST) | Vol. 11, N0. 1.
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| 8 | Ofomata, A. I. O., Inyama, S. C., Umana, R. A. and Omame, A. (2017). | A Stochastic Model of the Dynamics of Stock Price for Forecasting | In this work, a stochastic model of some selected stocks in the Nigerian Stock Exchange (NSE) is formulated. We considered four different stocks and their market prices. The likelihood of each change occurring in the stock prices was noted, the drift (the expectation) and the volatility (the covariance) of the change were computed leading to the formulation of stochastic differential equations. Changes in the prices of the stocks were studied for an average of 60 days. The drift and the volatility coefficients for the stochastic differential equations were determined and the Euler-Maruyama method for system of stochastic differential equations was used to simulate the stock prices. With the aid of the simulation we carried out a fore-cast of the prices of the stocks for a short time interval. A consideration of the different stock prices over a period of forty months, stock S1 seems to give the best return on investment compared with stocks S2, S3 and S4. The investor after observing the trend over longer period can invest in the stock that will yield the best returns. Our analysis enables us to compare as many as four stocks in order to advise the investor on where best to make investment. | Journal of Advances in Mathematics and Computer Science, | 25(6): Pp.1-24
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| 9 | Okore, K. E. O., Inyama, S. C., Nwobi, F. N. (2017). | Mathematical Model of Municipal Solid Waste ManagementSystem in Aba Metropolis of Abia State Nigeria; | In this study, mathematical model of municipal solid waste management system (MSWMS) is presented for Aba metropolis. The mixed integer programming problem was used in formulating the (MSWMS) model. The formulated model was solved using MATLAB 2015a version. The optimal results show that the best model would include 3 landfills, 322 tons capacity Collection Centers and seven (7) Collection Centers. The proposed model results in a minimum transportation cost of ₦3, 929, 900 per day as against the sum of ₦5,600, 000 per day which is currently spent on solid waste disposal in Aba according to ASEPA. The study went further to show that any additional increase on the collection center capacity up to 350 tons will result in upward rise and fall of the objective function value. The study finally concluded that in order to improve solid waste management in Aba, the emerging conditions for the adoption and operation of the MSWMS model needs to be addressed through a number of institutional reforms and management designs and arrangement includingstakeholder collaborations, encouraging informal sector participation and the development of technological innovations for solid waste management. | Quest Journals, Journal of Research in Applied Mathematics | Volume 3 ~ Issue 7 pp: 38-51
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| 10 | Okore, K. E., Inyama, S. C., Nwobi, F. N. (2017). | Mathematical Model And The Economic Analysis of Solid Waste Disposal In Aba Metropolis | In Kalu et al. (2017) we looked at Mathematical Model of Municipal solid waste management system in Aba metropolis of Abia State of Nigeria. In this particular paper we carried out the economic analyzed the solid waste disposal in Aba. We analyzed the data collected in Kalu, et al. (2017). When the effect of the capacity of the collection center was carried out, it was observed that minimum cost falls with rise in capacity of the collection centre. It is seen that the number and permutation of collection centres to be opened for minimum cost of the transportation network is independent of the scavenged fraction, but the quantities moved and at optimal and the minimum transportation cost is affected by scavenged fraction. These results confirm the expectation that rise in scavenged fraction will cause a fall in minimum transportation cost and the quantities moved to the landfills. The analysis further reveals that when the collection centers are designed to have the maximum capacities of C=350 with other factors being equal, the minimum cost becomes ₦3,948,700.00 and 7 out of the 15 collection centers are open and thus in use. It is also seen that the best way to minimize the burden of payment on the customers while guaranteeing reasonable daily profit to the investor and tax return to the government is to increase the capacity of the collection centers and optimal place to locate them. | Quest Journals, Journal of Research in Applied Mathematics | Volume 3 ~ Issue 7 (2017) pp: 52-66.
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| 11 | Nwadibia, A. I., Eze, F., Inyama, S. C., Nse, C. A., Omame, A. and Mbachu, H. I. (2018). | Mathematical Model of the Transmission Dynamics of Genital Elephantiasis (Lymphatic Filariasis) | In this study, mathematical model of municipal solid waste management system (MSWMS) is presented for Aba metropolis. The mixed integer programming problem was used in formulating the (MSWMS) model. The formulated model was solved using MATLAB 2015a version. The optimal results show that the best model would include 3 landfills, 322 tons capacity Collection Centers and seven (7) Collection Centers. The proposed model results in a minimum transportation cost of ₦3, 929, 900 per day as against the sum of ₦5,600, 000 per day which is currently spent on solid waste disposal in Aba according to ASEPA. The study went further to show that any additional increase on the collection center capacity up to 350 tons will result in upward rise and fall of the objective function value. The study finally concluded that in order to improve solid waste management in Aba, the emerging conditions for the adoption and operation of the MSWMS model needs to be addressed through a number of institutional reforms and management designs and arrangement including stakeholder collaborations, encouraging informal sector participation and the development of technologicalinnovations for solid waste management. | Mathematical Theory and Modeling | Vol.8, No.4, pp. 71—113,
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| 12 | Agwu, I. A, Inyama, S. C., Umana, R. A., Omame, A., Ukanwoke, N. , Ofomata, A., Mbachu, H. I., Udofia, E. S., Uwakwe, J. I. (2018). | Determining the Impact of Variation of Harvesting Effort on the Qualitative Behaviour of a Coexistence Steady State Solution and Its Stability in Prey-Predetor Fishery Model, | In this paper, we consider a prey-predator fishery model in a three –patch aquatic habitat with selective harvesting of predator and prey populations. We attempt to study the qualitative behaviour of stability and co-existence steady state solution in an interaction between prey and predator populations due to variation of the harvesting effort when other model parameters are fixed using the method of numerical simulation. The innovation of this simulation technique has been used to determine the fraction of harvest and un-harvest resource biomass for prey and predator populations. Explicit expressions and values of the maximum sustainable yield (MSY) and the corresponding populations’ level are obtained. Some sort of control is suggested to avoid over exploitation of resource biomass. Graphical solutions of the model are provided. | Academic Journal of Applied Mathematical Sciences | Vol. 4, Issue: 10, pp: 119-128,
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| 13 | Omame, A., Umana, R. A., Okuonghae, D. and Inyama, S. C., (2018). | Mathematical analysis of a two-sex Human Papillomavirus (HPV) model | A two-sex deterministic model for Human Papillomavirus (HPV) that assesses the impact of treatment and vaccination on its transmission dynamics is designed and rigorously analyzed. The model is shown to exhibit the phenomenon of backward bifurcation, caused by the imperfect vaccine as well as the re-infection of individuals who recover from a previous infection, when the associated reproduction number is less than unity.Analysis of the reproduction number reveals that the impact of treatment on effective control of the disease is conditional, and depends on the sign of a certain threshold unlike when preventive measures are implemented (i.e. condom use and vaccination of both males and females). Numerical simulations of the model showed that, based on the parameter values used therein, a vaccine (with 75% efficacy) for male population with about 40% condom compliance by females will result in a significant reduction in the disease burden in the population. Also, the numerical simulations of the model reveal that with 70% condom compliance by the male population, administering female vaccine (with 45% efficacy) is sufficient for effective control of the disease. | International Journal of Biomathematics | Vol. 11, No. 7, 1850092 (43 pages
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| 14 | Uwakwe, J. I., Inyama, S. C., Nse, C. A. and Emerenini, B. O. (2018). | Stability Analysis And Control Of Coccidiosis Disease In Poultry | In this paper, we formulate a multi – group model of the Coccidiosis disease with eight (8) compartments. The susceptible birds are divided into two groups, latently infected birds are divided into three groups, infected birds are divided into two groups according to infectivity and the recovered birds. A deterministic model was formulated and analyzed using methods from dynamical systems theory. Conditions for the stability of the disease-free and endemic steady states were determined. The stability analysis shows that the disease-free equilibrium (DFE) is locally stable if μ > r1b and μ > r2b. The endemic equilibrium (EE) is locally stable if 𝐸2>𝛽𝐼2𝑟1𝑏−𝜇−𝐼2 𝑎𝑛𝑑 𝐸2>𝛽𝐼2𝑟2𝑏−𝜇−𝐼2. The global stability of DFE and EE were proved using Lyapunov method. We then investigated the relative impact of each of the constant parameters on the basic reproduction number (R0), using the concept of sensitivity analysis. Three control measures were introduced. The control v1(t) represents the control variable based on bird vaccination, v2(t) the control variable based on good poultry management practices and v3(t) the control variable to measure the effectiveness of anticoccidial drugs. The Optimal Control approach is used to find the best strategy to fight the disease and minimize cost. The economic evaluation involved in the use of these control measures was also considered. Finally, a numerical solution (simulation) of the model was carried out to gain more insight on the dynamics of the disease. | IOSR Journal of Mathematics (IOSR-JM) | Volume 14, Issue 6 Ver. I (Nov - Dec 2018), PP 31-40
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| 15 | Emerenini, B. O. and Inyama, S. C. (2018). | Mathematical model and analysis of hepatitis B virus transmission dynamics | Hepatitis B is a potentially life-threatening liver infection caused by the hepatitis B virus (HBV). In this paper, the transmission dynamics of hepatitis B is formulated with a mathematical model with considerations of different classes of individuals, namely immunized, susceptible, latent, infected and recovered class. The role of vaccination of new born babies against hepatitis B and the treatment of both latently and actively infected individuals in controlling the spread are factored into the model. The model in this study is based on the standard SEIR model. The disease-free equilibrium state of the model was established and its stability analyzed using the Routh-Hurwitz theorem. The result of the analysis of the stability of the disease-free equilibrium state shows that hepatitis B can totally be eradicated if effort is made to ensure that the sum of the rate of recovery of the latent class, the rate at which latently infected individuals become actively infected and the rate of natural death must have a lower bound. | F1000Research | 1.202777778
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| 16 | Okoro,V.M.O.; Ejiogu, G.E.; Okoli,I.C.; Anyanwu, G.A,;Ezeokeke, C.T.;and Okoro, C.I. (2012). | Biometric measurements of body and internal organ traits of indigenous chickens on free range in south Eastern, Nigeria. | A biometric study of the body conformation and internal organs of the indigenous chickens of free ranges in rural areas of Imo State in South-Eastern Nigeria was conducted using 5 local government areas. It was observed that the predominant plumage colours were black (51.25%) and brown (36.25%) for the hens while the cocks were predominantly black (30.36%) and red (25.01%). The dressed colour of the birds was majorly yellow and while comprising of (70.68%) and (29.32%) for the hens and (77.75%) and (22.25%) for the cocks, respectively. Shank colour was black (95.4%) and white (4.65%) for the hens. While the cocks were (54.24%) black and (46.76%) white respectively. The mean shank length, neck length and back length of 6.725±0.30 cm 11.11±0.20cm and 17.77±0.29 cm were estimated for the hens, while the cocks had mean shank length, neck length and back length of 7.79±0.13cm, 11.35±0.30 cm and 18.29±0.44 cm, respectively. The mean body weights of the hens and cocks were 868.48±21.18g, and 1032±57.84g, respectively with cocks being significantly (P<0.05)higher in body weight and back length than hens. The mean biometric and internal organ measures of chickens per local Government Area (LGA) were also investigated with no significant (P>0.05) differences among chickens in the five LGAsexcept for weight of proventriculus and full intestine. Regression equations for the prediction of body weight using the biometric and internal organ measurements were obtained under two functional forms (linear and semi-log) which showed a weak coefficient of determination (R2) ranging between 7.5 to 24.3% for biometric measurements, and a strong coefficient of determination (R2) ranging between 21.4 to 98.89% for internal organs. There was no significant correlation (r) shown between internal organs and body weight. Therefore, indigenous chickens of South-Eastern Nigeria exhibit wide variability among phenotypesin terms of physical appearance, biometric measurement and internal organ characteristics. More so, the internal organs can be predicted more effectively than biometric measurements by the body weight, using regression models of the two functional forms; and significant indirect selection can be made to improve internal organs like gizzard weight using the bodyweight, due to significant correlation coefficient established. | Nigerian Journal of Animal Production. Vol. 39 (11) pp 14-23 | pp 14-23. ISSN 0331-2064.
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