AU Journal of Technology

Editorial

2015-10-02T16:41:22+00:00

The first issue of the eighteenth volume of AU Journal of Technology contains contributions from the fields of biotechnology, software engineering, technological innovation and materials engineering.

Production and Characterization of Protease from Serratia marcescens

2015-10-02T16:41:22+00:00

Extracellular protease produced by Serratia marcescens isolated from the gut of termite (Centrocestus formosanus) was investigated in this study. The effect of temperature, pH, carbon and nitrogen sources on protease production was examined. The extracellular protease was separated from the culture supernatant of the organism through precipitation with ammonium sulfate. The protease was purified by Sephadex G-150 gel filtration and diethylaminoethanol (DEAE) - Sephadex A-50 ion exchange chromatography. The effect of temperature, pH, and salts on the proteolytic activity of the enzyme was also investigated. Optimal protease production was obtained after about 12-hour incubation. The optimum temperature and pH for protease production was found to be 40°C and pH 7, respectively. Protease production was highest when rice bran and casein were used as the carbon and nitrogen sources, respectively. The native molecular weight of the protease was estimated to be 56 kDA. The optimal temperature for hydrolysis of casein was 50°C and the optimal pH was 8. The protease was found to be inhibited by ethylenediaminetetraacetic acid (EDTA), NaCl, CaCl2, FeCl2 and HgCl2. Proteolytic activity was however enhanced by KCl. The maximum velocity Vmax and Km values were 40 mg/min/mL and 0.91 mg/mL, respectively.

Adsorption of Heavy Metals from Wastewaters Using Adonosia digitata Fruit Shells and Theobroma cacao Pods as Adsorbents: A Comparative Study

2015-10-02T16:41:23+00:00

In this study, adsorption of heavy metal ions using activated carbon from Adonsonia digitata fruit shells and Theobroma cacao pods was carried out to comparatively evaluate their effectiveness as adsorbents for the purpose of removing Pb2+ and Cd2+ from synthetic wastewaters. Adosonia digitata fruit shells (ADFS) were collected within Yola and its environs, Adamawa State, Nigeria, whereas Theobroma cacao pods (TCP) were collected from the divisional office of the Cocoa Research Institute of Nigeria (CRIN) in Ikom, Cross River State, Nigeria. Both samples were crushed resulting in particle sizes of about 300-450 µm and the physicochemical as well as the adsorption properties of the activated carbon produced from both adsorbents were studied. Effects of some process parameters have been investigated in this study as well by following a batch adsorption technique at 32 ± 2oC. The percentage removal of Pb2+ and Cd2+ was found to increase with the decrease of the initial concentration of metal ions and to increase with the increase of the contact time and the adsorbent dose. The monolayer adsorption capacity, Qo for Pb(II) was found to be 41.20 mg/g and 29.89 mg/g for ADFS and TCP, respectively, whereas the monolayer adsorption capacity Qo for Cd(II) was found to be 34.39 mg/g and 25.10 mg/g for ADFS and TCP, respectively. In conclusion, it was observed that activated ADFS had a higher monolayer adsorption capacity for Pb2+ and Cd2+ than activated TCP.

An Investigative Study of Corrosion Effects of Cereals on the Grinding Components of Commercially Available Grinding Machines

2015-10-02T16:41:23+00:00

This study investigates corrosion effects of household food products such as cereals on commercially available grinding machines. Samples of grinding machine materials, such as alloys of cast iron and mild steel, were exposed to water and to two identified cereal environments, i.e. corn and sorghum in solution. The loss in weight of the alloy samples in the various environments were determined over pre-determined intervals. The corrosion rates of the alloys were then determined from analysis and found to be 15.314 W/T and 13.863 W/T for cast iron and mild steel, respectively, where W is the weight loss and T is exposure time. It was discovered that corn had more corrosive effects on the alloy samples as compared to sorghum. Furthermore, cast iron has higher corrosion rate than mild steel. This research work reveals the extent of corrosion on grinder materials in cereal environments and so would aid the foundry men in appropriating the chemical composition of the alloys to suit such environment.

Investigating the Kinetics of Biodesulfurization of Diesel

2015-10-02T16:41:23+00:00

The technology of biodesulfurization requires that reactors, where the reaction can take place, must be designed. In order to do this, the kinetics of the process must be thoroughly understood. This work aims to investigate the kinetics of biodesulfurization of diesel. This was done by simulating the kinetics of the process alone and then with and without the effect of mass transfer. The kinetic parameters, maximum rate constant, νmax, and the Michaelis-Menton constant, KM, were estimated using the linear equations of Hanes, Lineweaver-Buck and Eadie-Hofstee. The values obtained for each of the parameters from the linear equations were close but are not the same. This necessitated the need to carry out a non-linear regression analysis on the substrate concentrationtime data. The analysis was done using Marquardt’s algorithm of non-linear regression analysis. The obtained results were then compared with experimental data, they both showed good correlation with the experimental data although the mass transfer influenced kinetics showed a better agreement with the experimental data. Based on the aforementioned findings, one may conclude that mass transfer played an important role in the kinetics of biodesulfurization of diesel.

An Exploratory Survey of Phase-wise Project Cost Estimation Techniques

2015-10-02T16:41:24+00:00

This article explores a number of existing project cost estimation techniques to investigate how the estimation can be done in a more accurate and effective manner. The survey looks into various estimation models that utilize many theoretical techniques such as statistics, fuzzy logic, case-based reasoning, analogies, and neural networks. As the essence of conventional estimation inaccuracy lies in life cycle cost drivers that are unsuitable to be applied across the project life cycle, this study introduces a phase-wise estimation technique that posits some overhead and latency costs. Performance evaluation methods of the underlying phase-wise principle are also presented. Contributions of this phase-wise approach will improve the estimation accuracy owing to less latency cost and increase the project visibility which in turn helps the project managers better scrutinize and administer project activities.

Book Review A Review of “The Global Innovation Index 2014: The Human Factor in Innovation” (Editors: Soumitra Dutta, Bruno Lanvin and Sacha Wunsch-Vincent)

2015-10-02T16:41:24+00:00

Dutta, S.; Lanvin, B.; and Wunsch-Vincent, S. (eds.) 2014. The Global Innovation Index
2014: The Human Factor in Innovation. Cornell University, Ithaca, New York, NY,
USA; Institut Européen d'Administration des Affaires (INSEAD), Fontainebleau, Île-deFrance,
France; and World Intellectual Property Organization (WIPO), Geneva, Switzerland.
Available: <http://www.globalinnovationindex.org/userfiles/file/reportpdf/GII-
2014-v5.pdf>.

A Comparison between Different Materials Based on Transition Metal Oxides as Additivesfor Laser Bonding on Stainless Steel

2015-10-02T16:41:24+00:00

In this work, a new modification of the laser bonding is considered. Only one specific transition metal oxide is used to create an additive coating on a stainless surface. The following materials have been selected for comparative analysis: MoO3, WO3 and a commercial laser bond ink produced by TherMark. Temperatures over 2,000 K at the focal spot, with a very steep temperature increasing front of 107 K/s and spatial gradients of 107 K/m, have been evaluated. The mechanical properties of the coating have been studied by ramp scratch and Vickers hardness tests. The structural state and adhesive properties have been studied by X-ray diffraction (XRD) and Raman spectroscopy. A spectrophotometer has been used to estimate the contrast. The experimental results show a hard coating with excellent adhesion to the substrate with a thickness of several m. The presence of intermediated oxides has been detected, which is an indication of oxidation processes. The good adhesion is explained by a chemical bond between the oxide and the substrate.