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.

Medicinal plant Syzygium guineense (Willd.) DC Leaf Extract Mediated Green Synthesis of Ag Nanoparticles: Investigation of their antibacterial activity

Abstract: The medicinal plant, Syzygium guineense (Willd.) DC mediated green silver nanoparticles (SyG-Ag NPs) were successfully synthesized for the first time in Ethiopia. The synergistic influence of biomolecules of the plant leaf extract such as alkaloids, phenolic compounds, tannins, saponins and glycosides with Ag NPs towards the antibacterial activity has been investigated. The synthesized nanoparticles were characterized by UV-Vis, UV-DRS, FT-IR, XRD, SEM, EDXA, TEM, HRTEM and SAED techniques. The presence of absorbance maxima, λmax at 452 nm confirms the formation of SyG-Ag NPs. The energy gap, Eg of NPs, was found to be 2.1 eV. FTIR spectra confirmed the presence of biomolecules in the extract and NPs. The presence of 4 sharp peaks in the XRD pattern of NPs confirmed highly crystalline nature of NPs. The purity of the NPs was confirmed by SEM-EDAX analysis. The average particle size of NPs was found to be 27.62 nm. TEM-HRTEM-SAED analysis resulted in d-spacing values of 0.2396 nm which corresponds to Ag (111) lattice fringes of SyG-Ag NPs. The d-spacing value of the derived diffraction planes from 4 major spots; d111Ag = 0.2428 nm, d200Ag = 0.2056 nm, d220Ag = 0.1483 nm and d311Ag = 0.1263 nm, are in agreement with the XRD data. The antibacterial test results showed synergistic effect against both Gram positive bacteria, S. aureus (11±0.04 mm), and Gram negative bacteria E. coli (12±0.012 mm), P. aeruginosa (10±0.1 mm), and E. aerogenes (13±0.032 mm), respectively, proving potentiality of SyG-Ag NPs as a remedy for infectious diseases caused by tested pathogens.

Numerical Study of Temperature Distributions and Solidification Pattern in the Weld Pool of Arc Welded Plate

Abstract: The study on heat flow in welding is essential as the quality of the weld depends on mainly heat flow through the welded plate. The heat input from welding source flows in a limited zone, and it subsequently flows into the workpiece by conduction. In this study, an attempt is taken to predict the transient temperature distribution and solidification pattern through a numerical model and the associated mathematical technique considering the solidification and heat transfer, of molten weld pool when it is covered with flux and without flux in arc welding process. The numerical model developed in this study solves fluid flow and heat transfer considering solidification and melting phase change the along with natural convection in the meltpool. It was found that the flux is functioning as insulation on the welded pool, hence it restricts rapid solidification and increases the mushy zone width.

Sediment Influx and Its Drivers in Farmers’ Managed Irrigation Schemes in Ethiopia

Abstract: Excessive soil erosion hampers the functioning of many irrigation schemes throughout sub-Saharan Africa, increasing management difficulties and operation and maintenance costs. River water is often considered the main source of sedimentation, while overland sediment inflow is overlooked. From 2016 to 2018, participatory research was conducted to assess sediment influx in two irrigation schemes in Ethiopia. Sediment influx was simulated using the revised universal soil loss equation (RUSLE) and compared to the amount of sediment removed during desilting campaigns. The sediment deposition rate was 308 m3/km and 1087 m3/km, respectively, for the Arata-Chufa and Ketar schemes. Spatial soil losses amounts to up to 18 t/ha/yr for the Arata-Chufa scheme and 41 t/ha/yr for the Ketar scheme. Overland sediment inflow contribution was significantly high in the Ketar scheme accounting for 77% of the deposited sediment, while only 4% of the sedimentation at the Arata-Chufa scheme came from overland flow. Feeder canal length and the absence of canal banks increased the sedimentation rate, however, this was overlooked by the stakeholders. We conclude that overland sediment inflow is an often neglected component of canal sedimentation, and this is a major cause of excessive sedimentation and management problems in numerous irrigation schemes in sub-Saharan Africa.