Browsing by Author "Getachew, Negash"

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    Benign Methods for the Synthesis of Metal Organic Frameworks (MOFs)
    (Addis Ababa University, 2013-06-06) Getachew, Negash; Chebude, Yonas (PhD)
    The recent interest in the synthesis of hybrid inorganic–organic solids (metal organic frameworks or MOFs) gives a new dimension to the domain of porous compounds. They offer new scientific and technological opportunities by combining attractive features of both porous solids and organometallics. Most of them are prepared under mild hydrothermal conditions using functionalized organic ligand and organic amines. Hence there is a need to develop an environmentally green and energetically favorable method in the synthesis of these materials. The main challenge behind the synthesis of MOFs under benign conditions is the insolubility of the organic linkers in most of the common solvents. In this work, different MOFs have been synthesized using water as a solvent for the metal salts. Some of these are known MOFs [MOF-2, HKUST-1 and MOF-74 (Zn)] while others are uncommon phases. Using a linker salt (disodiumterephthalate or Na2BDC), two of the most popular MOFs: MIL-53(Al) (MIL=Material of Institute Lavoisier) and MOF-5 [Zn4O(BDC)3] have been synthesized at room temperature. Especially MIL-53(Al) or aluminum - 1,4-benzenedicarboxylate was synthesized at room temperature using water as a solvent for the first time. The linker salt approach can be applied as a general strategy consisting in the use of linker salts as an alternative to the exclusively tested acidic form of the linker (protonated linkers). The method does not only imply the prevention of the undesirable corrosive synthesis medium, but it also introduces substantial differences in terms of solubility of the linker, and pH of the medium. Hence, a novel method in the synthesis of metal organic framework materials has been developed under environmentally benign conditions. - Spanish cooperation Agency for financing my research undertaking in Spain - A.A.U. for giving me an opportunity to pursue my graduate studies I would like to appreciate and bless my mother W/O Almaz, my brothers (Seyoum, Meseret, Abreham and Eyob) and my sisters (Genet, Tigist, Amelework, Abaynesh and Muluken) for their prayers, unreserved help and encouragement throughout the course of this work. My heartfelt appreciation and gratitude goes to my family; my soul mate and companion of my life Mesti, my son Muse and my daughter Bethel for their endless support, prayer, love and sacrifice.
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    Causes and Remedies of Language Endangerment: The Case of Zay
    (AAU, 2020-02) Getachew, Negash; Meyer, Ronny (PhD)
    This study was conducted with the purpose of looking into the causes and remedies of the endangered minority Zay language. With this end in view, mixed methods design was used in the study. In fact, the study is more of qualitative, and the quantitative method was used for triangulation purposes. Quantitative data was gathered using questionnaires. Participants who filled out the questionnaire were drawn from the island and mainland residents via quota-sampling technique. The qualitative data was collected by means of key informant interview, in-depth interview and FGDs. Apart from this, ethnically Oromo people were interviewed to find out their attitudes towards Zay language. In all cases, informants were selected through purposive sampling technique. Further, observation was conducted to confirm the soundness of data procured by the use of other qualitative tools. While the qualitative data was analyzed through thematic analysis, the quantitative one was dealt with using statistical techniques. The study found out that both the external and internal factors accounted for the shortfall of mother tongue speakers of Zay, particularly in the younger generation. The Zay confronted a problem of making living in their traditional settlement areas, because of which a sizeable number of people left the islands for the nearby lakeshore villages and towns. The other was absence of willingness from part of the government to recognize Zay as a distinct ethnic group, as well as exclusion of the language from any secondary domains. Part of the people tended to develop low opinion of themselves and their language as a result. No less important were historical factors, such as recurrent conflict with the dominant Oromo people over land and water which was said to have pushed part of the Zay people, who already settled along the lake shores, back to the islands. This situation caused the introduction of late marriage (in order to control population boom) as the resources on the islands were limited. Cultural and linguistic factors were also found to contribute to the diminution of the language. These external forces appeared to put pressure on the attitudes of the Zay and their language use behavior. There were people who developed low opinion of their ancestral language where, in some cases, the pride in being Zay seemed to be fading. In the same way, the finding emerged from the respondents of Oromo people revealed the presence of negative attitudes towards Zay language. However, the majority were still found to maintain their loyalty to their language. They regarded their distinctive language as a central part of their identity. When it comes to language use, almost all people on the islands of Lake Zway have still used the Zay language; in the rest of the areas where Zay people live, the shift to Afan Oromo has been progressing. The change in speech behavior, particularly on the mainland, resulted in structural consequences. That is, change in Zay‟s lexicon, phonology, morphology, and in rare case syntax is noticeable. The results of the study show the presence of strong desire among the Zay to see their ethnic language reinvigorated. There was a strong belief among the respondents that changing the attitudes of the Zay and Oromo people who developed low impression of the language, improvement of the poor living standards of the people, establishment of Zay-medium primary school and creation of mother tongue based literacy education, above all, official recognition of Zay would be the possible restorative strategies. A further major finding was that the Zay were waking up to the threat and gradually being more adamant in their demands for greater official recognition and support of their language. The Zay have been struggling for official ethnic recognition and political representation because they believed that achieving this opportunity could certainly pave the way for changes in their overall economic, political and social lives which would in turn lead to reinvigoration of their language. The Zay community also established a self-help association (ZDA) with the purpose of solving its economic and social problems, thereby protecting its language and culture.On the basis of the findings, the researcher recommended that community members as well as out-group members‟ threatening attitude should be changed since it is a cornerstone for the success of all actions. The regional government should ensure sedentary settlement on the islands through building the capacity of the people to achieve a self-sustaining economic unit. Mother tongue primary education and Zay Cultural Center should also be made available to the Zay if the language and culture are to survive into the next generation.
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    A Comparative Study of the Methods of Teaching Reading Employed by the Televised Teacher and the Classroom Teacher With Especial Reference To Grade Nine Students of Jimma Town Senior Secondary Schools
    (Addis Ababa University, 2008-02) Getachew, Negash; Mohammed, Nuru (PhD)
    The main objective of this study is to compare the methods of teaching reading employed by the televised teacher and classroom teachers. The study was conducted at Jiren and Setto Senior Secondary Schools of Jimma Town. The former is Plasma and the latter is non-Plasma school. The subjects of the study were grade nine students and English language teachers of the aforementioned schools. 410 students (210 from Plasma and 200 from non-Plasma school), and 6 teachers (three from each school) were randomly selected as source of data. To collect the necessary information from the subjects, three data collection instruments (classroom observation, questionnaire and interview) were used. The findings showed that the method of the teaching reading employed by the televised teacher was found to be relatively different from the classroom teacher. The televised teacher employed the teaching methods that assured students' active involvement in the reading activities, and that provided enough opportunity for students to interact with each other in pairs and groups. On the other hand, the classroom teacher used method of teaching reading, where students' involvement in learning through interaction among themselves, was more or less negligible. Only oral question-and-answer work, where the role of majority students was not that of active participants, was the predominant classroom practice of the teachers, i.e. students were given no more chances to communicate or interact among themselves. Compared to the televised teacher, the classroom teacher did not employ the classroom procedures which help students comprehend the text better and practice the important sub skills (such as skimming and scanning) of reading. Besides this, unlike the televised teacher, the classroom teachers predominantly practiced reading aloud instead of silent reading. Most of the class time of reading lessons was employed for reading aloud by students. Based on the findings it was concluded that relative to the classroom teachers, the televised teacher seems to employ the techniques and procedures that experts and researchers of reading propose. However, there are areas that are found difficult for the televised teacher but easy for the classroom teacher and the vice versa. It was, therefore, recommended that reading should be better taught by the televised teacher with active involvement of the classroom teacher.
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    Studies on First Rowtransition Metal Complexes Derived from Ninhydrin and Amino Acids Having Polar(Threonine) and Nonpolar(Leucine) Side Chains
    (Addis Ababa Universty, 2003-06) Getachew, Negash
    Complexes of Co(II), Ni(II), and Zn(II) with Ruhmann’s purple, those of Fe(III) and Mn(II) with an intermediate Schiff base ( ketimine and / or aldimine) and Cu(II) with ninhydrin were successfully synthesized. All complexes were distinctly colored and stable to atmospheric conditions. The complexes were characterized by elemental analysis, molar conductance, magnetic susceptibility, infrared and electronic spectral studies. The ligands were shown to behave as a monobasic tridentate ONO, bidentate ON or OO donor. The complexes of Zn(II), Co(II) and Ni(II) are purely Ruhmann’s purple, those of Mn(II) and Fe(III) are Schiff base (ketimine), Schiff base and ninhydrin or Schiff base and Ruhmann’s purple complexes. An octahedral geometry is proposed for all of the metal complexes, except Mn(II). A comparative anti- microbial study of the complexes was undertaken against two gram - negative bacteria, Escherichia coli and one gram - positive bacterium Staphylococcus aureus. It was revealed that except Cu(II) and to some extent Zn(II) complexes most of the complexes exhibit a reduced activity against both bacterium. KEY WORDS: metal complexes, Schiff base, ninhydrin, Ruhmann’s purple, ᾳ– Leucine, ᾳ–L–Threonine and antimicrobial activity