Kinetic and Thermodynamic Studies of the Adsorption of Cr(VI) onto Some Selected Local Adsorbents

In this study, locally available biomasses obtained from avocado kernel seeds (AKS), Juniperus procera sawdust (JPS) and papaya peels (PP) were investigated as adsorbents for the removal of Cr(VI). The study employed a batch method to investigate the efficiency of the adsorbents. Parameters that influence adsorption such as: pH, adsorbent dose, initial concentration of Cr(VI), contact time and temperature have been studied. Optimum parameters for the adsorption of 5mg L–1 Cr(VI) were: pH: 1, adsorbent dose: 0.5 g, contact time: 160 min and temperature: 313 K. The equilibrium data was best fitted to the Freundlich adsorption isotherm model. The results of kinetic models showed that the pseudo-second-order kinetic model was found to correlate well to the experimental data. The results of thermodynamic parameters showed that the adsorption process is feasible. The positive values of the entropy change suggest increased randomness at solid-liquid interfaces during the adsorption. The efficiencies of the adsorbents towards the removal of chromium from real samples were also examined and were found to remove chromium from waste water.KEYWORDS Adsorption, chromium (VI), avocado kernel seed, papaya peel, Juniperus procera sawdust, local adsorbent, adsorption kinetic, Thermodynamic of adsorption

Prevalence and Predictors of Atrial Fibrillation and its Embolic Complications in Patients with Rheumatic Heart Disease at Tikur Anbessa Specialized Hospital, Addis Ababa, Ethiopia

Background: Atrial fibrillation is one of the complications of rheumatic heart disease, with substantial morbidity and mortality. The prevalence and predictors of atrial fibrillation and its thrombo-embolic complications in Ethiopian patients with rheumatic heart disease are unknown. The objective of this study was to determine the prevalence and predictors of atrial fibrillation and its thromboembolic complications.Methods: A retrospective chart review of 500 patients with rheumatic heart disease at the adult cardiology clinic of Tikur Anbessa Specialized Hospital was carried out from 01 January to 31 June 2016. Data were entered into a pre-tested questionnaire and were analyzed using SPSS version 23.Results: Records of 500 patients (72% female) with electrocardiographic recordings and echocardiographic reports were available for analysis. Atrial fibrillation was found in 234 (46.8%) of the patients. Predictors of atrial fibrillation were found to be: age ≥50 years (p=0.01), left atrial size ≥45mm (p=0.01), the presence of mitral stenosis (p<0.01) and the presence of tricuspid regurgitation (p=0.01). Cardioembolic events were reported in 67 (9.2%) patients, and the presence of atrial fibrillation (p=0.02) and sub-therapeutic anticoagulation status (p<0.01) were significant predictors of cardioembolic events.Conclusions and recommendations: The study reveals a high prevalence of atrial fibrillation and cardioembolic events in Ethiopian patients with rheumatic heart disease. Hence, active screening of atrial fibrillation and optimal anticoagulation are recommended. [Ethiop. J. Health Dev. 2019;33(1):12-16]Key words: Rheumatic Heart Disease, Atrial Fibrillation, Cardioembolic Complications, Stroke, Ethiopi

Evaluation of the Water Footprint of Beef Cattle Production in Nebraska

Data were compiled on feed usage to model the amount of water needed to produce beef in typical Nebraska production systems. Production systems where cows were wintered on corn residue utilized 18% less water than systems utilizing native range as a wintering source, because of water allocations. Therefore, the water footprint (gallons of water required to produce one pound of boneless meat) was decreased by 18%. In addition, increasing the dietary inclusion of distillers grains from 0% to 40% decreased the water footprint in the finishing phase by 29%, again based on water allocation. Utilizing corn residue and distillers grains in Nebraska beef cattle systems decreases the overall water footprint of production. Additionally, the water footprint of the systems analyzed was 80% green water as rain, minimizing the environmental impact of beef production on freshwater use and ecological water balance

A practical approach for minimising inbreeding and maximising genetic gain in dairy cattle

A method that predicts the genetic composition and inbreeding (F) of the future dairy cow population using information on the current cow population, semen use and progeny test bulls is described. This is combined with information on genetic merit of bulls to compare bull selection methods that minimise F and maximise breeding value for profit (called APR in Australia). The genetic composition of the future cow population of Australian Holstein-Friesian (HF) and Jersey up to 6 years into the future was predicted. F in Australian HF and Jersey breeds is likely to increase by about 0.002 and 0.003 per year between 2002 and 2008, respectively. A comparison of bull selection methods showed that a method that selects the best bull from all available bulls for each current or future cow, based on its calf's APR minus F depression, is better than bull selection methods based on APR alone, APR adjusted for mean F of prospective progeny after random mating and mean APR adjusted for the relationship between the selected bulls. This method reduced F of prospective progeny by about a third to a half compared to the other methods when bulls are mated to current and future cows that will be available 5 to 6 years from now. The method also reduced the relationship between the bulls selected to nearly the same extent as the method that is aimed at maximising genetic gain adjusted for the relationship between bulls. The method achieves this because cows with different pedigree exist in the population and the method selects relatively unrelated bulls to mate to these different cows. Selecting the best bull for each current or future cow so that the calf's genetic merit minus F depression is maximised can slow the rate of increase in F in the population