Akoy E.,Al Fashir University |
Von Horsten D.,University of Gottingen |
Ismail M.,University of Khartoum
International Food Research Journal | Year: 2013
Moisture adsorption isotherms of solar-dried mango slices (cv. Kitchener) were determined at three temperatures (20°C, 30°C and 40°C) for a water activity (aw) range of 0.111 to 0.813 using the standard static gravimetric method. The sorption characteristic of solar-dried mango slices followed type III (J-shaped) isotherms, characteristic of high sugar products. An intersection of the curves occurred at aw=0.75 for the investigated temperatures, which indicates the occurrence of the reverse temperature effect. The experimental equilibrium moisture content data were subsequently fitted to two well-known mathematical sorption models; namely, the BET and GAB models. Non-linear regression analysis was used to evaluate the models' parameters. The validation of the two selected models was done by using statistical parameters: the mean relative percentage deviation (% P) and the coefficient of determination (R2). The estimated parameters of the GAB model were correlated to temperature. The (K) parameter of GAB model was found to increase with temperature, whereas the monolayer moisture content (Mo) decreased with increasing temperature. The Arrhenius-type relationships of the GAB parameters were determined. The GAB model was satisfactorily used to predict the equilibrium moisture content (EMC) of solar dried-mango slices.
Harran I.,Southwest Jiaotong University |
Harran I.,Al Fashir University |
Wang H.,Southwest Jiaotong University |
Chen Y.,Southwest Jiaotong University |
And 2 more authors.
Journal of Alloys and Compounds | Year: 2016
The high pressure (HP) structural phase of FeB2 compound is investigated by using first-principles crystal structure prediction based on the CALYPSO technique. A thermodynamically stable phase of FeB2 with space group Imma is predicted at pressure above 225 GPa, which is characterized by a layered orthorhombic structure containing puckered graphite-like boron layers. Its electronic and mechanical properties are identified and analyzed. The feature of band structures favors the occurrence of superconductivity, whereas, the calculated Pugh's ratio reveals that the HP Imma structure exhibits ductile mechanical property. © 2016 Elsevier B.V. All rights reserved.
Akoy E.O.M.,Al Fashir University
International Food Research Journal | Year: 2014
Convective air drying characteristics of mango slices at different drying temperatures (60°C, 70°C and 80°C), at an air velocity of 0.5 m/s and for constant sample thickness (3 mm) were investigated. Results indicated that drying took place in the falling rate period. Drying time decreased considerably with increased drying temperature. Three mathematical models; namely, Newton (Lewis), Henderson and Pabis, and Page were selected to describe and compare the drying characteristics of mango slices. Comparisons were based on the coefficient of determination (R2), sum square error (SSE), root mean square error (RMSE) and reduced-chi square (χ2). Among the tested models, the Page model achieved the best fit. Moisture transfer from mango slices was described by applying the Fick's diffusion model. Effective moisture diffusivity (Deff) values increased with increasing drying temperature and were found to range from 4.97 x 10-10 m2/s to 10.83 x 10-10 m2/s. The temperature dependence of the effective diffusivity was described by the Arrhenius-type relationship and the activation energy for the diffusion of the moisture associated with the mango slice was found to be 37.99 kJ/mol. © 2008 IFRJ, Faculty of Food Science & Technology, UPM.
Mansour K.,University of KwaZulu - Natal |
Mansour K.,Al Fashir University |
Mutanga O.,University of KwaZulu - Natal |
Adam E.,University of KwaZulu - Natal |
And 3 more authors.
Geocarto International | Year: 2016
Land degradation is believed to be one of the most severe and widespread environmental problems. In South Africa, large areas of land have been identified as degraded, as shown by the lower vegetation cover. One of the major causes of grassland degradation is change in plant species composition that leads to presence of unpalatable grass species. Some grass species have been successfully used as indicators of different levels of grassland degradation in the country. This paper, therefore explores the possibility of mapping grassland degradation in Cathedral Peak, South Africa, using indicators of grass species and edaphic factors. Multispectral SPOT 5 data were used to produce a grassland degradation map based on the spatial distribution of decreaser (Themeda triandra) and increaser (Hyparrhenia hirta) species. To improve mapping accuracy, soil samples were collected from each species site and analysed for nutrient content. A t-test and machine learning random forest classification algorithm were applied for variable selection and classification using SPOT 5 data and edaphic variables. Results indicated that the decreaser and increaser grass species can be mapped with modest accuracy using SPOT 5 data (overall accuracy of 75.30%, quantity disagreement = 2 and allocation disagreement = 23). The classification accuracy was improved to 88.60%, 1 and 11 for overall accuracy, quantity and allocation disagreements, respectively, when SPOT 5 bands and edaphic factors were combined. The study demonstrated that an approach based on the integration of multispectral data and edaphic variables, which increased the overall classification accuracy by about 13%, is a suitable when adopting remote sensing to monitor grassland degradation. © 2015 Taylor & Francis.
Yousif I.,University of Khartoum |
Fadlelmoula A.,University of Khartoum |
Ismail A.,Al Fashir University
Archiv fur Tierzucht | Year: 2011
Data on 586 kids from 30 bucks and 120 does of Sudan desert goats was used in the present study. The study aimed at investigating the genetic variations of body weight at various ages. Range of heritability estimates for body weight from birth to 6th month was 0.04-0.54. The estimates from dam component ranged 0.28-0.68 which was higher than that from sire component estimates. The genetic correlations for body weight at various ages were substantially high, ranged from 0.51-0.99 as sire, dam and dam nested in sire components. Phenotypic correlations of body weight at various ages ranged from 0.43-0.99 with differences being significant (P<0.01). Low to high environmental correlations (0.10-0.33) were encountered as dam component. However, the random effect of sire was found to be significantly (P<0.01) positively correlated. © Leibniz Institute for Farm Animal Biology, Dummerstorf, Germany.