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In this study, a simple and selective biosensor has been introduced for determination of lactose by potentiometric method based on the catalytic behavior of kefir grains via modification with multi-walled carbon nanotubes (MWCNTs)/casein composite as indicator electrode and sat’d Ag/AgCl as reference electrode. To fabricate the indicator electrode, kefir grains were initially dried using a freeze dryer during 48 h time interval and powdered with an electronic grinder. Then ~ 0.15 g kefir powder was physically mixed with MWCNTs/casein with optimized weight ratio of 0.005/0.3 (w/w) and mixed with ~ 150 µL nujol oil. The generated paste was then packed inside a Teflon tube (i.d: 10 mm, height: 100 mm) and adopted as indicator electrode. Maximum potentiometric response was also observed at pH 7.0 and 0.51 M ionic strength, controlled using phosphate buffer (0.01 M) and NaCl (0.5 M), respectively. The linear dynamic range during lactose determination was ranged between 1.0×10-12 - 1.0×10-4 M with detection limit of 3.0×10-14 M based on extrapolation definition. Small hysteresis (lower than ~4%) was observed during sequential analyses of several lactose solutions with different molar concentrations. The response time based on the 90% of maximum response (t90) was estimated to be ~2 min. The validity of this method was evaluated via direct determination of lactose in some types of milk samples. This biosensor was applicable for indirect lactose determination via estimation of the end point of lactose-containing milk sample during titration by a dilute HCl solution (1.0 mM) as titrant.

Background and objectives: The production and productivity of dry beans in Ethiopia is hindered by multiple challenges; among these were biotic, abiotic and socioeconomic factors. Thus, this review paper highlighted and discussed those factors that impose dry beans not to give reasonable grain yield and acceptable quality there by to identify and discuss the main challenges of common beans under the study area, and to document the information generated from the paper for future improvement of dry beans. Material and Methods: A number of peer reviewed papers were critically viewed and reanalyzed based on the current situation of legumes production. Based on the investigation and observations made the author distinguished and prioritized the major threats of beans production for the study area. Results: Via different sources, information generated. The author also identified and prioritized the agents that limit the production of dry beans under the area and means of managing the challenges separately or by integration them. Conclusion: Therefore, the author recommend and suggest that to cultivate our farmlands in sustainable way we have to follow and apply the cropping patterns and systems of rotation with legumes to achieve this we must made bridge between technology generated with producers.