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Search Results: 1 - 10 of 524621 matches for " I. T. M. Usman "
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M. A. Usman,T. O. Alaje,V. I. Ekwueme,T. E. Adekoya
Petroleum and Coal , 2012,
Abstract: The work investigated the feasibility of the catalytic degradation of water sachet waste (which is a low density polyethylene) to produce valuable chemicals using 12-tungstophosphoric acid (HPA) and 12-tungstophosphoric acid supported on KIT-6 as catalysts. The reaction was carried out at 400°C for 30 minutes at atmospheric pressure. The gas and liquid products obtained were analyzed using a gas chromatograph. For the liquid product using HPA-KIT-6, about 69 mol% of fractions between C10-C17 (kerosene fraction) was obtained; 32 mol% of which was C16 fraction while for the gas product 93 mol% propane fraction was obtained. A low amount of gas (mainly C3 fraction) resulted from the reaction using HPA-KIT-6 while cracking over HPA gave high yield of gas product (C2 and C3 fractions). Catalytic degradation using HPA/KIT-6 is therefore a promising route for obtaining valuable fuels and petrochemicals while at the same time reducing the environmental problems arising from water sachet waste.
Characterization, Acid Activation, and Bleaching Performance of Ibeshe Clay, Lagos, Nigeria
M. A. Usman,V. I. Ekwueme,T. O. Alaje,A. O. Mohammed
ISRN Ceramics , 2012, DOI: 10.5402/2012/658508
Investigation of the Catalytic Performance of a Novel Nickel/Kit-6 Nanocatalyst for the Hydrogenation of Vegetable Oil
M. A. Usman,T. O. Alaje,V. I. Ekwueme,E. A. Awe
ISRN Chemical Engineering , 2012, DOI: 10.5402/2012/526852
Investigation of the Catalytic Performance of a Novel Nickel/Kit-6 Nanocatalyst for the Hydrogenation of Vegetable Oil
M. A. Usman,T. O. Alaje,V. I. Ekwueme,E. A. Awe
ISRN Chemical Engineering , 2012, DOI: 10.5402/2012/526852
Abstract: Highly ordered mesoporous materials are opening the door to new opportunities in catalysis due to their extraordinary intrinsic features. In this study, Nickel was supported on highly ordered mesoporous silica (KIT-6) by the wet impregnation method, and its performance in the hydrogenation of edible vegetable oil was compared with that of Ni/Activated carbon prepared using the same method as well as with unsupported Nickel. The degree of conversion for the 50?:?50 Ni/KIT-6 was 81%, as compared to the 29% obtained with 50?:?50 Ni/Activated carbons. The conversion was found to improve with an increase in mass of supported Nickel on KIT-6 thus 20?:?80 Ni/KIT-6 and 30?:?70 Ni/KIT-6 produced conversions of 71% and 74%, respectively. Key among the benefits of KIT-6 when used as a support material is the very high surface area, open framework of the 3D bicontinuous interconnected channels, and the well-ordered mesopores which bestow on it an advanced mass transfer characteristics. 1. Introduction Catalytic hydrogenation is a very important reaction in the synthesis of organic compounds which dates back to 1897 when Paul Sabatier, a French Chemist [1], discovered that the introduction of a trace of nickel metal enabled the addition of hydrogen to molecules of hydrocarbon compounds. Since then, it has been widely used in various fields, which include industrial hydrogenation processes such as the synthesis of methanol, liquid fuels, hydrogenated oils, cyclohexanol, and cyclohexane. In the food industry, hydrogenation is applied to process vegetable oils and fats [2]. Unsaturated vegetable fats and oils can be hydrogenated by the catalytic addition of hydrogen at the ethylenic linkages of their acids to produce saturated or partially saturated fats and oils of higher melting point. The most common forms are shortening, margarines, and the partially hydrogenated fats used for frying and in processed food. These fats are desirable for their melting point, which allows for high temperature cooking and frying. With rare exception, no reaction below 480°C occurs between H2 and organic compounds in the absence of metal catalysts [3]. The catalyst binds both the H2 and the unsaturated substrate and facilitates their union. The catalytic cycle starts with oxidative addition of an H2 molecule to the metal centre to give a metal dihydride species and ends with reductive elimination of the product [4, 5]. Because these complexes are difficult to remove and reuse, numerous attempts have been made to anchor the catalysts on organic or inorganic supports to combine the
The Influence of Silane Gas Flow Rate on Optoelectronic Properties of mc-Si:H Prepared by HWC-VHF-PECVD Technique
T. Winata,I. Usman
ITB Journal of Science , 2008,
Abstract: Hydrogenated microcrystalline silicon (mc-Si:H) thin films have been deposited using 10% silane (SiH4) in H2 dilution by Hot Wire Cell Very High Frequency Plasma Enhanced Chemical Vapor Deposition (HWC-VHF-PECVD) technique. The resulted thin film characteristics were systematically studied as a function of the deposition parameter. The previous structural studies showed that the structural phase transition from amorphous to microcrystalline thin film was obtained using the filament temperature of 800 oC. In this study, the optoelectronic properties of mc-Si:H thin films were investigated as a function of the silane gas flow rate from 40 sccm to 80 sccm. The highest deposition rate of 3.6 /sec and the lower optical bandgap of 1.4 eV were obtained using 80 sccm and 60 sccm of the silane gas flow rate, respectively. The film showed the photosensitivity of 3 x 107, which is quite high above the minimal value of 103 for solar cell application.
On Cycle Related Graphs with Constant Metric Dimension  [PDF]
Murtaza Ali, Gohar Ali, Usman Ali, M. T. Rahim
Open Journal of Discrete Mathematics (OJDM) , 2012, DOI: 10.4236/ojdm.2012.21005
Abstract: If G is a connected graph, the distance d (u,v) between two vertices u,v ∈ V(G) is the length of a shortest path between them. Let W = {w1, w2, ..., wk} be an ordered set of vertices of G and let v be a vertex of G . The repre-sentation r(v|W) of v with respect to W is the k-tuple (d(v,w1), d(v,w2), …, d(v,wk)). . If distinct vertices of G have distinct representations with respect to W , then W is called a resolving set or locating set for G. A re-solving set of minimum cardinality is called a basis for G and this cardinality is the metric dimension of G , denoted by dim (G). A family ? of connected graphs is a family with constant metric dimension if dim (G) is finite and does not depend upon the choice of G in ?. In this paper, we show that dragon graph denoted by Tn,m and the graph obtained from prism denoted by 2Ck + {xkyk} have constant metric dimension.
Evidence for Nodal superconductivity in Sr$_{2}$ScFePO$_{3}$
K. A. Yates,I. T. M. Usman,K. Morrison,J. D. Moore,A. M. Gilbertson,A. D. Caplin,L. F. Cohen,H. Ogino,J. Shimoyama
Physics , 2009, DOI: 10.1088/0953-2048/23/2/022001
Abstract: Point contact Andreev reflection spectra have been taken as a function of temperature and magnetic field on the polycrystalline form of the newly discovered iron-based superconductor Sr2ScFePO3. A zero bias conductance peak which disappears at the superconducting transition temperature, dominates all of the spectra. Data taken in high magnetic fields show that this feature survives until 7T at 2K and a flattening of the feature is observed in some contacts. Here we inspect whether these observations can be interpreted within a d-wave, or nodal order parameter framework which would be consistent with the recent theoretical model where the height of the P in the Fe-P-Fe plane is key to the symmetry of the superconductivity. However, in polycrystalline samples care must be taken when examining Andreev spectra to eliminate or take into account artefacts associated with the possible effects of Josephson junctions and random alignment of grains.
Influence of Desiccation Time on Survival and Regeneration of Embryonic Axes of Groundnut (Arachis hypogaea L.) Immersed in Liquid Nitrogen  [PDF]
M. M. Abdulmalik, I. S. Usman, J. D. Olarewaju, D. A. Aba
American Journal of Plant Sciences (AJPS) , 2013, DOI: 10.4236/ajps.2013.49211

Cryopreservation, the storage of biological materials in liquid nitrogen (LN), is a useful method for long term conservation of plant germplasm. This study was carried out with the objective of establishing an efficient desiccation technique for successful cryopreservation and recovery of embryonic axes of groundnut. Embryonic axes of four groundnut (Arachis hypogaea L.) genotypes were evaluated. The excised embryonic axes were dehydrated by air current of a laminar air flow cabinet for different duration (0, 1, 2, 3, 4 & 5 hrs) before being plunged in LN (-196℃) and held for 1 hr. Samples were thawed in water bath at 40℃ for 2 min, thereafter cultured on MS medium supplemented with 15 mg/L BAP for recovery. Highest survival (96.67%-100%) and shoot formation (91.67%-96.67%) were obtained at an average moisture content of 17% after 4-5 hr desiccation. Among the genotypes evaluated, Samnut 22 and Samnut 23 recorded the highest

Agronomic Efficiency of Cowpea Varieties (Vigna unguiculata L. Walp) under Varying Phosphorus Rates in Lafia, Nasarawa State, Nigeria
I.M. Haruna,A. Usman
Asian Journal of Crop Science , 2013,
Abstract: Savanna soils of Nigeria are inherently low in nutrients (particularly nitrogen and phosphorus) thereby resulting in low yield of crops. To this end, field experiments were conducted at the Teaching and Research Farm of College of Agriculture Lafia in the Southern guinea savanna zone of Nigeria (08°30'N and 08°30'E, 18 m above sea level) during the rainy seasons of 2009, 2010 and 2011 to evaluate the yield and agronomic efficiency of cowpea varieties under varying phosphorus application rates. The experiment consisted of four levels of phosphorus in the form of single super phosphate (0, 30 and 60 kg P ha-1) and four varieties (DAN ILA, IAR-48, IT90K-277-1 and IT93K-452-1). The twelve treatment combinations were laid out in a randomized complete block design with three replications. The results obtained showed that number of pods per plant, pod yield per plant, seed yield per plant, number of seeds per pod, 100 seed weight and seed yield per hectare were significantly increased by the application of 30 kg P ha-1 in all the years of the experiment. Variety IT90K-277-1 consistently produced significantly, the highest values for all yield and yield characters measured. Agronomically, application of 30 kg P ha-1 was significantly more efficient than 60 kg P ha-1. Application of 30 kg P ha-1 to variety IT90K-277-1 produced significantly, the highest seed yield per hectare and is therefore recommended.
Effects of Heat Treatment on Strength and Ductility of Rolled and Forged Aluminum 6063 Alloy  [PDF]
S. O. Adeosun, S.A. Balogun, O.I. Sekunowo, M.A. Usman
Journal of Minerals and Materials Characterization and Engineering (JMMCE) , 2010, DOI: 10.4236/jmmce.2010.98054
Abstract: This work examines the effect of heat treatment on tensile strength and ductile responses of rolled and forged AA6063 aluminum alloy. Some cast samples were rolled while some were forged at ambient temperature (32℃). The deformed samples were subjected to heat treatment processes. The tensile strengths of rolled (212 MPa) and forged (127 MPa) samples are enhanced at ambient temperature but with poor elongation responses. A combination of improved strength and elongation (127 MPa, 24%) can be obtained in rolled sample when solution heat treatment (SHT) is applied after deformation and cooling in water. The forged sample when homogenized, solution treated and water quenched has elongation of about 24% with improved strength of 137 MPa. These results were obtained because of the development of very fine AlFeSi texture in the matrix and along the grain boundaries.
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