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.

Compositional Evolution of Oxide Inclusions in Austenitic Stainless Steel during Continuous Casting

Abstract: Composition evolution and number density of oxide inclusions in austenitic stainless steel were investigated by analyzing inclusions in a commercial austenitic stainless steel slab. The composition of inclusions was observed to be strongly dependent on size of the inclusion and location in the slab, both, where the inclusions were found. The number density of inclusions increased as the inclusions were found at deeper location from the slab surface. The basicity (%CaO/%SiO2) of the inclusions decreased with decreasing the inclusion size, while the manganese oxide content (%MnO) increased with decreasing the inclusion size. As the inclusions were located deeper from the slab surface, the basicity (%CaO/%SiO2) was found decreased but (%MnO) increased. Such composition changes along with the position in the slab was attributed to the combination of pre-existing inclusions which were entrapped from the argon oxygen decaburization slag and inclusions precipitated during solidification due to decrease in solubility limit of concerned elements. A theoretical model was developed in order to represent the inclusion composition in the austenitic stainless steel during continuous casting, as a function of the size and location of the inclusion. The model predictions for the composition of inclusion, such as (%CaO/%SiO2), (%MnO), and Al2O3 content, were in good agreement with the measured data.

Chemical composition and antimicrobial activities of leaves of sweet basil (Ocimum basilicum L.) herb

Abstract: Background: Leaves and flowering parts of Ocimum basilicum are believed to be rich of different phytochemicals and are traditionally used as antispasmodic, aromatic, carminative, digestive, galactogogue, stomachic, and tonic agents. Hence , the study was designed to evaluate the phytochemical constituents and antimicrobial activities of the leaves of sweet basil ( O. basilicum ) herb. Methods: The leaf extract was used for screening of phytochemicals. A small amount of the powdered leaves of the plant was subjected to hydrodistillation to extract the essential oil, and the components of the essential oil were evaluated by gas chromatography-mass spectroscopy instrument. The extract was tested in vitro for its antibacterial activity against two bacteria; Escherichia coli and Staphylococcus aureus and antifungal activity against two fungi; Aspergillus niger and Rhizoctonia bataticola by paper disc diffusion method. Results: Results revealed the presence of many phytochemicals such as alkaloids, tannins, flavonoids, cholesterol, terpernoids, glycosides, phenols, cardiac glycosides, carbohydrates, and phlobatannins. The essential oil extracted from the leaves of O. basilicum was found to have estragole (38.22%) as a major constituent followed by 1-isopropyl-4-methylenecyclohex-1-ene (11.10%). Tests of antimicrobial activity showed that the hydrodistilled oil was effective against all the tested bacterial and fungal strains. However, the crude extract was found not to have antimicrobial activity toward the tested bacteria and fungi. Conclusion: So, the study has showed that the observed antimicrobial effect of O. basilicum essential oil on the bacterial and fungal isolate, though in vitro appear interesting and promising. So, emphasize have to made on the antimicrobial activities of the plant during the time of drug extraction.

Thermoelectric Transport Properties of n-Type Sb-doped (Hf,Zr,Ti)NiSn Half-Heusler Alloys Prepared by Temperature-Regulated Melt Spinning and Spark Plasma Sintering

Abstract: Herein we report a significantly reduced lattice thermal conductivity of Sb-doped Hf0.35Zr0.35Ti0.3NiSn half-Heusler alloys with sub-micron grains (grain size of ~300 nm). Polycrystalline bulks of Hf0.35Zr0.35Ti0.3NiSn1−xSbx (x = 0.01, 0.02, 0.03) with a complete single half-Heusler phase are prepared using temperature-regulated melt spinning and subsequent spark plasma sintering without a long annealing process. In these submicron-grained bulks, a very low lattice thermal conductivity value of ~2.4 W m−1 K−1 is obtained at 300 K due to the intensified phonon scatterings by highly dense grain boundaries and point-defects (Zr and Ti substituted at Hf-sites). A maximum thermoelectric figure of merit, zT, of 0.5 at 800 K is obtained in Hf0.35Zr0.35Ti0.3NiSn0.99Sb0.01.

Numerical simulation and experimental investigation on static behavior of cold formed steel beam with trapezoidally corrugated web by varying depth-thickness ratio

Abstract: This paper presents a numerical simulation and experimental investigation on the static behavior of cold-formed steel beams with trapezoidally corrugated web has been carried out to find its structural performance of simply supported beam under pure bending. The steel beams with corrugated steel webs represent a new innovative which has emerged in the past decade for short- and medium-span beams. The thin corrugated web affords a significant weight reduction of these beams, compared with hot-rolled beams. In the initial solution, the flanges are made of flat plates, welded to the trapezoidal web sheet, requiring a specific welding technology. The connecting between flanges to the web can be done by means of intermittent welding. The paper summarizes the experimental and numerical investigations carried out at the Hindustan University and, at the end, presents the flexural behavior of cold-formed steel beams with trapezoidally corrugated web. To find the effect of web corrugation, 12 experiments were conducted on cold-formed steel beams. Beams having two different web depth-thickness (dw/tw) ratio 60 and 80 and with three types of web corrugation angles 0°, 30° and 45° were tested. Two beams were tested in each series. The static performance of the three different corrugation angles, including failure mode, load–deflection curves, strength capacity, load–strain curves, moment–curvature curves, flexural stiffness and ductility, are compared and discussed in detail based on the experimental results. Finally, numerical analysis using ANSYS Workbench results are analyzed and the experimental results were validated with the results obtained from the finite element analysis.