Browsing by Author "Assefa, Teshome"
Item Computational Study on Hydrogen Bonded Complexes formed by Anthyridone and 2,6-diaminopyridine-3,5-dialdehyde and their Derivatives(Addis Ababa Universty, 2009-07) Assefa, Teshome; Mustefa, Ahmed (PhD)Computational study was performed on a hydrogen bonded complex formed by antyridone and 2,6-diaminopyridine-3,5-dialdehyde. Six other complexes were designed based on the structure of the complex by changing the R- group of monomer A in to C6H5, p-toluene, p-phenol, OH and OCH3, the X group of monomer B in to chlorine. The binding energies of the complexes were calculated based on their optimized geometry using DFT/B3LYP at 6-31 G level. The electronic spectra for the complexes were calculated with ZINDO and IR spectra of the monomers and complex 1 were computed using DFT/B3LYP at 6-31 G level. It was indicated that all complexes could be formed, via hydrogen bonds. Complexes 2 - 4 were hindered due to steric effect. Electron donating nature was the stability factor. The first absorptions in the electronic spectra of the complexes were red shifted compared with those of the monomers. The stretching vibrations of the N – H bonds were increased with the formation of the hydrogen bond. Key Words: antyridone, 2,6-diaminopyridine-3,5-dialdehyde, DFT and hydrogen bondItem The Effect of the Viscosity of Ready to Bake Teff Batter on the Weight and other Qualities of Injera(Addis Ababa University, 2017-10-02) Assefa, Teshome; Zewdu, Ashagrie (PhD)Some processing parameters like viscosity, fermentation time, baking time and other have an effect on the overall quality of injera. In this study, experiments were conducted to determine how viscosity affects weight of injera, which is an important injera criteria especially in the Injera bakery sectors. In the process of baking injera viscosity and weight of injera are the parameters which have impacts on the economic value in addition to other quality attributes of injera. The aim of this thesis work is to investigate whether there is correlation between viscosity of the batter ready to bake and the weight of injera. The raw materials Kuncho-white Teff (DZ-Cr-387), Magna-white Teff (DZ-01-196) and Asgori-brown Teff (DZ-01-99) grain varieties were collected from Debrezeit Agricultural Research Center (DZARC). Experimentation and processing of data were performed to study the correlation on the characteristics of batter and injera. The amylose content of the Kuncho-white Teff (DZ-Cr-387) (22.53%) was higher whereas the Magna-white Teff (DZ-01-196) (19.87%) the lowest. The pH of the batter was 3.86 – 4.11 while the pH for injera was 4.00 – 4.19. The maximum viscosity 24859m.Pa.S, 2083m.Pa.S and 16600m.Pa.S was showed by Asgori-brown Teff (DZ-01-99) at V1, V2 and V3 respectively. 17640m.Pa.S, 14632m.Pa.S and 10683m.Pa.S were the minimum viscosities respectively. From the Asgori-brown Teff (DZ-01-99) the highest weight of injera was- obtained for the whole viscosity category compared to the other teff and blended teff flour. The variable viscosity was found strongly correlated with the weight of injera (r = 0.947, P ≠ 0.00) with significant values. The regression curve for the variables viscosity and weigh was Y= 90.829x - 15131, R2 0.9149. The regression curve for each varieties was found Y = 190.96x – 49308, r2 = 0.9868 [Teff white (DZ-Cr-387)], Y = 192.36x – 47037, r20.968 [Teff White (DZ-01-196)], Y = 91.511x – 15566,r2 0.9956 [Teff brown (DZ-01-99)], Y= 91.01x-1030, r2 0.998 (Teff white (DZ-Cr-387)-Rice), Y= 139.78x – 31796, r2 0.9829 (Teff white (DZ-01-196)-Rice). Based on the results obtained it could be concluded the viscosity of the batter strongly correlated with the weight of injera.