Adama University

About: Adama University is a education organization based out in Nazrēt, Ethiopia. It is known for research contribution in the topics: Population & Adsorption. The organization has 840 authors who have published 1010 publications receiving 5547 citations. The organization is also known as: Adama Science and Technology University & ቴክኖሎጂ ዩኒቨርሲቲ, አዳማ ሳይንስና ቴክኖሎጂ ዩኒቨርሲቲ.

Formability analysis of aluminum alloys through deep drawing process

Abstract: Deep drawing process is a significant metal forming process used in the sheet metal forming operations. From this process complex shapes can be manufactured with fewer defects. Deep drawing process has different effectible process parameters from which an optimum level of parameters should be identified so that an efficient final product with required mechanical properties will be obtained. The present work is to evaluate the formability of Aluminum alloy sheets using deep drawing process. In which effects of punch radius, lubricating conditions, die radius, and blank holding forces on deep drawing process observed for AA 6061 aluminum alloy sheet of 2 mm thickness. The numerical simulations are performed for deep drawing of square cups using three levels of aforesaid parameters like lubricating conditions and blank holding forces and two levels of punch radii and die radii. For numerical simulation a commercial FEM code is used in which Hollomon's power law and Hill's 1948 yield criterions are implemented. The deep drawing setup used in the FEM code is modeled using a CAD tool by considering the modeling requirements from the literature. Two different strain paths (150x150mm and 200x200mm) are simulated. Punch forces, thickness distributions and dome heights are evaluated for all the conditions. In addition failure initiation and propagation is also observed. From the results, by increasing the coefficient of friction and blank holding force, punch force, thickness distribution and dome height variations are observed. The comparison has done and the optimistic parameters were suggested from the results. From this work one can predict the formability for different strain paths without experimentation.

Antibacterial Activity of Zingiber officinale on Escherichia coli and Staphylococcus aureus

Abstract: Aims: The aim of this study was to investigate the antibacterial activity of extracts of fresh, dried and oil of Zinginber officinale on Escherichia coli and Staphylococcus aureus. Minimum inhibitory concentrations of the extracts against test organisms were determined and their inhibitory effects were compared with commercially available antibiotics. Study Design: Laboratory based controlled experiment. Place and Duration of Study: The research was conducted at the Molecular Biology Laboratory, Department of Biotechnology, Modibbo Adamawa University of Technology, Yola, Nigeria between January and May, 2014. Methodology: Extracts from fresh and dried rhizomes of Z. officinale as well as ginger oil, which was extracted with the aid soxhlet extraction apparatus using n-hexane as the solvent were tested on isolates of E. coli and S. aureus using the agar well diffusion method. Both bacterial isolates were also subjected to standard antibiotic susceptibility test for comparison. Broth dilution method was used to determine the minimum inhibitory concentrations of the extracts on the test organisms. Results: At concentrations of 10 mg/mL, 20 mg/mL, 30 mg/mL, and 40 mg/mL the zones of Short Research Article Njobdi et al.; JABB, 19(1): 1-8, 2018; Article no.JABB.43534 2 inhibition of dried Z. officinale extracts on S. aureus were 11.00 ±1.41 mm, 13.5 ± 0.71 mm, 14.00± 2.66 mm and 17.5 ± 0.87 mm respectively and on E. coli were 6.00 ± 2.83 mm, 7.5 ± 2.12 mm, 8.00 ± 2.83 mm and 14.5± 6.08 mm respectively. Fresh ginger showed 15.00±1.40 mm and 12.00±2.83 mm at 100%, 50% concentrations respectively on S. aureus and 15.00±3.54 mm and 13.00±2.66 mm on E. coli respectively but has no effect at 25% and 12.5% on both organisms. The oil extract showed zones of inhibition of 12.00±2.83 mm and 7.00±4.24 mm at 100% and 50% concentrations on S. aureus respectively, while it showed no activity on E. coli. Minimum Inhibitory Concentration (MIC) of dried and fresh Z. officinale extracts on both isolates at 2.5 mg/ml. Oil extract did not exhibit inhibitory effect in broth even at concentration of 10 mg/ml. Conclusion: The study indicated that both fresh and dried Z. officinale extracts inhibit the growth of S. aureus and E. coli similar to some standard antibiotics. This suggests that the plant is a potential source of antibacterial drug.

Constructivist Didactics in Teaching Economics: A Shift in Paradigm to be Exemplary Teacher

Abstract: This paper begins with a theoretical analysis and critique of the prevailing behaviorist instructive which promotes a model of imparting and receiving knowledge in economics education. This approach is criticized for its inadequacy to facilitate higher order thinking, problem solving, creativity and collaborative learning. Contemporarily, research findings in cognitive learning shift the paradigm and provide new dimensions to information processing and constructivist view of teaching economics. It recognizes learners as constructor of knowledge and an active participant in the process of learning economic facts and principles, and economics teachers as facilitator of students’ learning. This theoretical paradigm in teaching economics doesn’t disvalue the instructional roles of teachers, rather it advocates that teaching economics should not only instructive but also constructive. Hence, this paper presents the philosophical and psychological roots and major pedagogical principles of constructivism, the rationale for adoption of traditional instructional perspectives with modern constructivist approach and its practical implications in teaching economics. Finally, it concludes that learning economics should not be only instructive, but also constructive. DOI: 10.5901/ajis.2013.v2n1p197