Abstract:The study was conducted to assess the contents of essential and non-essential metals in coffee beans. For this matter, seven essential metals such as K, Mg, Ca, Na, Mn, Cu and Zn and two nonessential metals (Cd and Pb) in four roasted coffee samples (washed Yirgacheffe, unwashed Yirgacheffe, washed Sidama and unwashed Sidama) were determined by FAAS. Closed microwave assisted wet digestion method with addition of concentrated (69-70%) HNO 3 and 30% H 2 O 2 were selected for decomposition of ground roasted coffee samples. Generally, the levels of metals in all roasted coffee samples were found: K > Mg > Ca > Na >Mn> Zn > Cu, but the non-essential metals Pb and Cd were found to be below method detection limit. The digestion method was evaluated by spiking roasted coffee samples and their percentage recoveries were in the range of 95 −104 %. It is suggested that the consumption of roasted coffee beans could be a source of dietary essential metals and a possible entrance path way for trace metals to the food chain.
The currently available antileishmanial drugs are either toxic or too expensive for routine use in developing countries where the disease is most common. Local people in the Somalia region of Ethiopia use the leaves of Aloe macrocarpa Todaro for the treatment of malaria, jaundice, and skin diseases. In our ongoing search for new, efficient, and safe antileishmanial drugs, we investigated the leaf latex of Aloe macrocarpa and its acid-hydrolyzed product aloin A/B (1), as well as the semisynthesized derivatives of aloin A/B, namely, aloe-emodin (2) and rhein (3) against promastigotes and axenically cultured amastigotes of Leishmania aethiopica and L. donovani clinical isolates. Activity study was carried out based on the fluorescence characteristic of resazurin added to drug-treated cultures. Oxidative hydrolysis of aloin A/B by ferric chloride and concentrated hydrochloric acid afforded aloe-emodin (2), which was further oxidized using sodium nitrite and concentrated sulfuric acid to furnish rhein (3). Cytotoxicity study of test substances was performed against human monocytic cell line THP-1 using Alamar Blue and cell viability was measured fluorometrically. The test compounds showed lower activity (IC50 = 6.7 to 12.1 μM for promastigotes and IC50 = 3.6 to 10.2 μM for axenic amastigotes) than the reference drug amphotericin B (IC50 = 1.3 to 2.7 μM). However, amphotericin B (LC50 = 11.1 μM) was much more toxic than the test compounds (LC50 = 369.2 – 611.6 μM) towards human monocytic cell line (THP-1) despite its efficiency. As demonstrated in the current study, high selectivity indices (SIs) of the test compounds represent a remarkable advantage over the reference drug and highlight their potential use as templates for further development of safe leishmanicidal drugs.
Abstract:For most developing countries, including Ethiopia Agriculture is the backbone of their economy. Due to lack of effective farm implements, theses country's population has been suffering on food shortage. Hence, the major objective the study is to improve the mechanical properties and abrasion resistance of traditional farm implements. To achieve the intended objectives of the study, Investigation was conducted on the mechanical and wear characteristics of steel samples for better performance of farm implements subjected to packed carburization treatment using wood coal as the carburizer, carburized at 850 °C, 900 °C and 950 °C, soaked at the carburizing temperature for 1:50 hrs followed by quenched with water. At the first the test specimen for analysis of different mechanical and wear characteristics of various local farming tools like abrasive wear, toughness, tensile strength, abrasive wear and hardness were prepared as per ASTM standard. The test specimens that was prepared for this purpose was subjected to destructive mechanical test before and after carburization process. From the data obtained, ultimate tensile strength, percent elongation, percent reduction in area, modulus of elasticity, Rockwell hardness, impact toughness, and abrasive wear were calculated. The destructive mechanical test results are compared before and after carburization process in order to see the impact of pack carburization and carburizing temperature on the performance (life cycle )of the traditional farm implements. It was observed that the mechanical properties of steel samples were found to be strongly influenced by the process of carburization, carburizing temperature and soaking time at carburizing temperature. It was concluded that the sample carburized at 950 °C soaked for 1:50 hrs followed by water quenching gives best result than the other samples. Since pack carburizing enhance the hardness, tensile strength, abrasion resistance, the farm implement manufacturing company has been recommended to carburize these farm implement.
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