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.

Design and analysis of sand casting process of mill roller

Abstract: The quality characteristics of the mill roller in sand casting has been affected by casting defects caused by in proper process parameter usage and intern affects its proper function that lead to large number of shop floor trials, high rate of rejection, and low casting yield. The objective of this research is to design and analyze sand casting process of mill roller. In this research work, methods like critical observation, interview, discussion, numerical experimentation, and simulation have been done. Solid modeling of mill roller component with all incorporating gating system has been carried out by solidwork software and simulation process has been carried out by using ProCAST software for the mold filling and solidification analysis to reduce the level and intensities of shrinkage porosities in cast mill roller. Taguchi method of numerical experimentations has been carried out for parameter optimization and analysis of variance (ANOVA) using Minitab software. The confirmatory test with the optimal level of casting process parameters have been carried out. The casting process parameters of the mill roller have been identified by using cause and effect diagram. The parameters such as permeability, pouring temperature, and moisture content have been taken into consideration. Based on the numerical results, their interpretation and the optimal values of the parameters have been determined to eliminate the defects. The present research work has shown in the improvement of casting yield. It has been found that the casting defects are minimized by 2.98%. The results also reveal that sand sintering problem and porosity defects occurred in the mill roller castings were due to the weak sintering strength of fine mixed molding silica sand used in the process. Using simulation software, shrinkage porosity has been observed in both gating system and roller part.

Participatory System Dynamics Mapping for Collaboration and Socioecological Integration in the Lake Tana Region

Abstract: This chapter presents a system map of causal links and feedback loops among social and ecological components in the Lake Tana region. The map was collaboratively developed by twenty-seven regional researchers, managers, and development experts who participated in a one-day systems mapping workshop entitled “Strengthening Links between Policy and Research for Sustainable Development in the Lake Tana Basin ” held in Bahir Dar, Ethiopia in November 2014. The chapter describes the map development process, content of the map, participant perspectives on the value of the process and the workshop outcomes, and steps for building on the workshop.

Profit Maximization in a Product Mix Company Using Linear Programming Approach to Resource Allocation

Abstract: This paper demonstrates the use of linear programming methods as applicable in the manufacturing industry. Data were collected as extracts from the records of Bajabure Industrial Complex (Nima Foam), Yola, Nigeria, on five types of sales packages adopted for selling their foam product which includes 15 density, 18 density, 20 density, 25 density and 29 density. Information on selling price and the cost of basic raw materials used as well as quantity of each of the raw material held in stock per month for the production of the foam were available in the records of the company. Based on the costs of raw materials, the maximum profit that would accrue to the company given the product mix was determined. The results showed that the company would attain optimal monthly profit level of about #524,369 if she concentrates mainly on the unit sales of her foam product, ignoring other forms sales packages. The analysis was carried out with R statistical package using library “lpSolve”.

Antibacterial and antioxidant activities of extracts and isolated compounds from the roots extract of Cucumis prophetarum and in silico study on DNA gyrase and human peroxiredoxin 5

Abstract: Cucumis prophetarum is traditionally used to treat liver and lung disorders, heart failure, diarrhea, gonorrhea, skin infections, intestinal problems and cancer. In the present work, the isolation of two novel compounds along with their antibacterial and antioxidant activities is reported for the first time. Silica gel column chromatography was applied to separate constituents of the roots of C. prophetarum. The structures of isolated compounds were established using 1H NMR, 13C NMR, DEPT-135, COSY, HSQC and HMBC. Agar well diffusion, DPPH assay and ferric thiocyante methods were used for antibacterial, radical scavenging and anti-lipid peroxidation activities, respectively. AutoDock Vina open source program was used for molecular docking analysis. Evaluation of the in vitro antibacterial activity of the constituents against S. aureus, B. subtilis, E. coli and S. thyphimurium revealed that the hexane extract were active against E. coli with IZ of 15.0 ± 1.41 mm, whereas an IZ of 14.6 ± 1.70 mm for MeOH extract was observed against S. aureus. Compound 1 displayed IZ of 13.6 ± 0.94 mm against E. coli and curcurbiatin 2 showed activity against B. subtilis with IZ of 13.3 ± 0.54 mm. The molecular docking analysis showed that cucurbitacins 2 and 3 have binding energy of -6.7 and -6.9 kcal/mol, respectively. The methanol and the hexane extracts of the roots of C. prophetarum inhibited DPPH radical by 70.4 and 63.3% at 100 µg/mL, respectively. On the other hand, the methanol extract inhibited lipid peroxidation by 53.0%. The present study identified five compounds from the root extracts of C. prophetarum, of which two are novel cucurbitacins (1, 2). The in vitro antibacterial activity of the hexane and methanol extracts was better than the activity displayed by the isolated compounds. This is probably due to the synergistic effects of the constituents present in the root extract. The in silico molecular docking study results showed that, compounds 2 and 3 have minimum binding energy and have good affinity toward the active pocket, thus, they may be considered as good inhibitor of DNA gyrase B. Furthermore, the “drug-likeness” and ADMET prediction of compounds 2–5 nearly showed compliance with the Lipinski rule, with good absorption, distribution, metabolism, and excretion generally. The radical scavenging and anti-lipid peroxidation activities of the extracts were better than the isolated compounds. This is attributed to the presence of phenolics and flavonoids as minor constituents in the extracts of these species. Therefore, the in vitro antibacterial activity and molecular docking analysis suggest the potential use of the isolated compounds as medicine which corroborates the traditional use of the roots of C. prophetarum.

Characterization Techniques and Evolution of Natural Polymer Nanofiber Composites (NPNFCs): An Extensive Study

Abstract: The twenty-first century witnessed the emergence of renewable resources—the application of composites in aerospace industry enhanced with carbon, glass, kevlar, etc. However, these materials are not biodegradable and environment-friendly. To solve this issue, studies were being carried out on natural composites which are biodegradable. The intent of this study is to present a comprehensive review of the biodegradable composites and matrix materials used in the aerospace industry. Since an aerospace vehicle has to operate under critical weather conditions at variable altitudes, the main problems with the existing materials are related to crash resistance, crack propagation rate growth, self-healing properties, and mechanical properties along with the additional problem of environmental pollution. The alternatives to synthetic fibers, thermoplastics, and thermosetting resins are biopolymers, natural fibers and natural fiber nanocomposites (NFNCs). NFNCs are already implemented in the automotive and aerospace industry because of their biodegradability. However, the type of reinforcement can predominantly alter the dynamic behavior of natural cellulose fiber—nanoparticle-embedded composites (NFNRCs). Similarly, the reinforcement surface-area-to-volume ratio is a key parameter for aerospace applications. Based on the type of reinforcement, nanofiller-based natural composites can display various effective enhancements in desirable properties (like an impact tolerance, fatigue strength, tensile and flexural strength), rheological properties, electrical conductive properties, optical properties, enhanced material durability, energy absorption rate, and shock/impact resistance that make these materials crucial for aerospace application. Based on this, a comprehensive study has been studied on NFNRCs.