Browsing by Author "Bekele, Tesfaye"

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    Analytical Application of the Membrane-Stabilized, Enzyme-Modified Interface Between two Immiscible Electrolyte Solutions
    (Addis Ababa Universty, 1995-06) Bekele, Tesfaye; Hundhammer, B.(PhD)
    An amperometric urea biosensor based on facilitated transfer of urease-generated ammonium ion by a neutral carrier (ionophore) dibenzo-18-crown-6 across the polarizable membrane-stabilized interface between water and nitrobenzene is described and discussed. The enzyme urease employed for the investigation was immobilized on the sensor surface by physical entrapment as a gel between dialysis membranes. The current response of the anlperometric sensor was found to be directly proportional to the concentration of urea in the sample solution. In addition, correction for residual current due to interfering (residual) substances is relatively easy. The sensor gave a linear response to urea in the concentration range 5 x 10" to 5 x 10.3 M. The response time of the sensor was I min. The sensitivity appeared to be dependent on the conditions of immobilization of the enzyme. The effect of the thickness of the enzyme layer on the sensor response has been discussed. The life time of the sensor was more than 3 weeks when stored in the buffer solution at room temperature
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    Seroprevalence of Contagiuos Caprine Pleuropnemonia in Borana and Gujilow Lands Southern Ethiopia
    (Addis Ababa University, 2008-06) Bekele, Tesfaye; Asfaw, Yilkal (PhD)
    A multi tage cr s ti nal erologicul study, que Ii nrHllr survcy and particip I ry apprai al were nducted n c ntagiou caprinc plcuropn umonia ( ' PI' fr m r. 2 07 to pril, 200 orana and uji 10\.\land , .'outh rn i-:.thiopiu. to determin the pn.:valcn of th id ntif) the ri k fact rs for the curren e of the di. ca ' and t a s th p~rception of the c mmunity on PP in parti ular and th r goat di . e in general. t tal f 951 erum sampl 900 from goats and 51 from h ep) were lIe ted and te ted u mg omplem nt Fixati n Te t ( FT). Que tionnaire ur ey were condu ted with 69 rand mly I cted hou ehold . Participatory di ea apprai al wa d ne \\ ith 12 in~ rmant gr up ' in 12 differ nt village th group size varying fr m 5-12 informant and with a t tal f 120 in~ rmant. ut of the 900 goat sera samples te ted 119 (13.2%) w re erop iti\e for PP, giving an overall seroprevalence of 13.2 % (95% I 11.0%-15.4%) in th tudyarea. r pr ",alence of 18.3% (95% 1=14.3%-22.7%), 11.6% (95% 1- 8%-15.2%) and 9.6% (950 /0 I 6. %-12.6% w re recorded in Liban, Teltale and Moyale District, re p ctively. h er pre\alenc rec rded among the district was significantly difD rent (p<0.05). Th r preval nc re orded in iban district was significantly different from that of Moyal Di trict (p<0.05). M r \ er, ut of 1 sheep samples tested, 3 (5.9%) wer eropo iti e. tati tical anal) i limed ri k fa tor howed that the roprevalence ob erved in ag gr up . fl ck ize gr up and di tan fr m et rinary service ntre were found t b ignificantl differ nt (p