Showing papers by "Adama University published in 2018"

Time Series Land Cover Mapping and Change Detection Analysis Using Geographic Information System and Remote Sensing, Northern Ethiopia

Abstract: Land use planners require up-to-date and spatially accurate time series land resources information and changing pattern for future management. As a result, assessing the status of land cover change...

Synthesis of nitrogen doped carbon quantum dots/magnetite nanocomposites for efficient removal of methyl blue dye pollutant from contaminated water

Abstract: As a remedy for environmental pollution, a simple synthesis approach has been developed to prepare nitrogen doped carbon quantum dot/magnetite nanocomposites (Fe3O4@NCQDs NCs) using non-toxic and cost effective lemon juice as precursor for removal of organic dye pollutant. Fe3O4@NCQDs NCs were characterized by using UV-Vis spectroscopy, FTIR, XRD, FESEM, EDS, TEM, VSM and TGA/DTA. TEM results show spherical shaped Fe3O4@NCQDs NCs with an average particle size of 5 nm. Batch adsorption studies were done to investigate the tendency of the nanocomposites to remove representative methyl blue (MB) dye from aqueous solution. The effects of MB dye concentration, dosage of Fe3O4@NCQDs NC adsorbent, pH, contact time and temperature were optimized by varying one variable while all the other parameters were kept constant. The experiment showed rapid removal of MB dye within 20 minutes with an adsorption efficiency of over 90.84% under optimum conditions. The adsorption process fits the Freundlich isotherm model well with R2 and n values of 0.993 and 1.842, respectively, at 298 K indicating the feasibility of the adsorption process. The adsorption process is spontaneous and involves exothermic behaviour as confirmed by thermodynamic studies. From a kinetic study, it was found that the pseudo-second order model is more suitable to describe the adsorption process than the pseudo-first order model for adsorption of MB dye onto Fe3O4@NCQDs NCs.

One-pot synthesis of sulfur and nitrogen codoped titanium dioxide nanorod arrays for superior photoelectrochemical water oxidation

Abstract: Despite its abundant, nontoxicity and photochemical stability, titanium dioxide shows low solar water oxidation performance due to low photogenerated carrier transport and wide optical band gap, which results in substantially low photogenerated carrier density that impair the solar to hydrogen conversion efficiency. Herein, highly enhanced water oxidation performance of high-aspect-ratio TiO2 nanorods doped with dual heteroatoms, sulfur and nitrogen, for photoelectrochemical solar water oxidation is demonstrated. The codoped TiO2 NRs have shown enhanced optical absorption coefficient due to the induced impurities energy states near to the top of the valance band and result in a red shift in the optical absorption edges. Consequently, a 2.82 mAcm−2 photocurrent density at 1.23 V vs. RHE is obtained from the sulfur and nitrogen codoped TiO2 nanorods, and pristine TiO2 nanorods photoanode shows 0.7 mAcm−2. The applied bias photon-to-current conversion efficiency and external quantum efficiency of the codoped TiO2 nanorods are 1.49% and 97.0% at λ = 360 nm and 0.69% and 19.1% at λ = 370 nm for pristine TiO2 nanorods, respectively. Our study offers experimental and theoretical evidence for codoping of sulfur and nitrogen improve the optical and electrical properties of TiO2 for efficient photoelectrochemical solar water oxidation.

Antibacterial and Antioxidant Compounds from the Flower Extracts of Vernonia amygdalina.

Abstract: Vernonia amygdalina is traditionally used in Ethiopia to treat various diseases. This prompted us to isolate bioactive compounds from the flowers of this plant. The CHCl3 extract after silica gel column chromatography has led to the isolation of two compounds identified as tricosane (1) and vernolide (2), while the acetone extract furnished isorhamnetin (3) and luteolin (4). The acetone extract and isorhamnetin significantly scavenged the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical by 91.6 and 94%, respectively. It was also shown that the acetone extract and isorhamnetin inhibited lipid peroxidation by 74 and 80%, respectively. The extracts and isolated compounds were also evaluated for their antibacterial activity with the CHCl3 extract and vernolide showing strong activity against S. aureus with an inhibition zone of 21 and 19 mm, respectively. On the other hand, the acetone extract and isorhamnetin were active against all bacterial pathogens tested. The work presented herein has demonstrated that vernolide and isorhamnetin had antibacterial activity. The antioxidant activity displayed by the flowers of V. amygdalina is accounted to the presence of isorhamnetin. Therefore, the biological activities displayed by the extracts and isolated compounds from this plant corroborate the traditional uses of this plant by the local people against various diseases.

Enhancement of chondrogenesis of adipose-derived stem cells in HA-PNIPAAm-CL hydrogel for cartilage regeneration in rabbits

Abstract: Injectable thermoresponsive hydrogels have the advantages of effective cell delivery and minimal invasion for tissue engineering applications In this study, we investigated the chondroinductive potential of newly developed hyaluronic acid (HA)-modified thermoresponsive poly(N-isopropylacrylamide) (HA-PNIPAAm-CL) hydrogels on enhancing rabbit ADSC (rADSC) chondrogenesis in vitro and in the synovial cavity of rabbit The HA-mixed PNIPAAm (HA-PNIPAAm-CP) and HA-cross-linked PNIPAAm (HA-PNIPAAm-CL) were fabricated using physical interaction and chemical cross-linking methods, respectively The in vitro results showed that, compared to unmodified PNIPAAm, both HA-modified hydrogels significantly increased cell viability, chondrogenic marker gene (aggrecan and type II collagen) expression and sulfide glycosaminoglycan (sGAG) formation in embedded rADSCs However, HA-PNIPAAm-CL showed the highest rADSC viability and chondrogenesis The chondrogenic effects of HA-modified hydrogels on rADSCs were confirmed in vivo by the intraarticular injection of hydrogel-embedded rADSC constructs into rabbit synovial cavities for 3 weeks and tracing with CM-DiI labeling Neocartilage formation in the hydrogels was determined by histomorphological staining of GAG and type II collagen In vivo injected rADSC/HA-PNIPAAm-CL constructs showed more hyaline cartilage formation than that of rADSC/HA-PNIPAAm-CP and rADSC/PNIPAAm constructs in the synovial cavity of rabbit These results suggest that the HA-PNIPAAm-CL provides a suitable microenvironment to enhance ADSC chondrogenesis for articular cartilage tissue engineering applications

An Epidemiological Trend of Urogenital Schistosomiasis in Ethiopia

Abstract: Schistosomiasis is a major public health problem in Ethiopia. Currently, the prevalence of the disease can possibly be heightened due to man-made ecological transformations particularly related to the recent development programs involving irrigation and construction of dams. The expansion of some of the water resource development projects has been cited enhancing the upsurge of urogenital schistosomiasis mainly in the lower altitude areas of the country. In connection to the extensive initiation of development projects in low altitude areas of the country, simultaneous and adequate attentions have never been given to address a pre-assessment of health impacts of the development programs prior to launching the projects. Helpful appraisals focusing on evaluation of epidemiology of urogenital schistosomiasis in Ethiopia have not been explored. Therefore, the current review attempts to trace an overall picture of the epidemiological status of urogenital schistosomiasis in the country; the past and existing trends of urogenital schistosomiasis surveys and control programs of the country are reviewed. Essential recommendations are highlighted for possible inputs in future control design strategies of national control program of schistosomiasis.

Anthropogenic impact on land use land cover: influence on weather and vegetation in Bambasi Wereda, Ethiopia

Abstract: Land Use Land Cover Changes (LULCC) has impacts on a wide range of environmental and landscape attributes including the quality of land, water and air. The main objective of this study was to analysis the impact of anthropogenic activities and LULCC on weather (rainfall and temperature) and vegetation in the study area over a period of 28 years. The study has employed temporal LANDSAT sensors data to identify the changes in LULC and Vegetation Indices through anthropogenic influence. Moreover, statistical analysis of temperature and rainfall data (1985–2015) has also been done of Bambasi station. It has been found that the average temperature has been increased approximately 2.2 °C and the average rainfall amount was declined throughout the period. The drastic changes have been noticed in LULC, vegetation health and its area through NDVI during the first interval (1987–2001) but the land change growth was less in second interval (2001–2015). The increasing population, urbanization and resettlement scheme for refugees were the responsible factors for changes. This case study indicates that the impact of anthropogenic activities leads the change in LULC and the climate has been influenced or vice versa over the time period in this semi-arid region of Ethiopia.

Privacy preserving data publishing based on sensitivity in context of Big Data using Hive

Abstract: Privacy preserving data publication is the main concern in present days, because the data being published through internet has been increasing day by day. This huge amount of data was named as Big Data by its size. This project deals with the privacy preservation in context of big data using a data warehousing solution called hive. We implemented nearest similarity based clustering (NSB) with Bottom-up generalization to achieve (v,l)-anonymity which deals with the sensitivity vulnerabilities and ensures the individual privacy. We also calculate the sensitivity levels by simple comparison method using the index values, by classifying the different levels of sensitivity. The experiments were carried out on the hive environment to verify the efficiency of algorithms with big data. This framework also supports the execution of existing algorithms without any changes. The model in the article outperforms than existing models.

Cyanobacteria and microcystins in Koka reservoir (Ethiopia).

Abstract: The composition and abundance of cyanobacteria and their toxins, microcystins (MCs), and cylindrospermopsins (CYN) were investigated using samples collected at monthly intervals from the Amudde side of Koka Reservoir from May 2013 to April 2014. Cyanobacteria were the most abundant and persistent phytoplankton taxa with Microcystis and Cylindrospermopsis species alternately dominating the phytoplankton community of the reservoir and accounting for up to 84.3 and 11.9% of total cyanobacterial abundance, respectively. Analyses of cyanotoxins in filtered samples by HPLC-DAD and LC-MS/MS identified and quantified five variants of MCs (MC-LR, MC-YR, MC-RR, MC-dmLR, and MC-LA) in all samples, with their total concentrations ranging from 1.86 to 28.3 μg L−1 and from 1.71 to 33 μg L−1, respectively. Despite the presence and occasional abundance of Cylindrospermopsis sp., cylindrospermopsin was not detected. Redundancy analysis (RDA) showed that the environmental variables explained 82.7% of the total variance in cyanobacterial abundance and microcystin concentration. The presence of considerably high levels of MCs almost throughout the year represents a serious threat to public health and life of domestic and wild animals.

Synthesis and Characterization of Ti-Fe Oxide Nanomaterials for Lead Removal

Abstract: TiO2-Fe2O3 binary oxides containing different percentage of Fe2O3 were synthesized using impregnation method. The Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDX), and thermogravimetric with differential thermal analyzer (TG-DTA) analytical techniques were used for understanding of the physicochemical properties and well impregnation of Fe2O3 in TiO2 lattice. During adsorption study, pH of the solution, adsorbent dosage, time of contact, agitation speed, and concentration of adsorbate were optimized. From Langmuir, Freundlich, FG, D-RK, Temkin, and FH adsorption isotherm models, relatively, Langmuir isotherm model fits well. For adsorption-reaction kinetic model, pseudo-first order (PFO), pseudo-second order (PSO), and Elovich were tested and intraparticle diffusion (IPD) for adsorption-diffusion kinetic models. Out of those, the PSO fits well; this indicates that the mechanism of adsorption is under control of adsorption-reaction. The mean adsorption energy, spontaneity, and reproducibility of the adsorbent were also conducted, and all of those studies support the domination of physical adsorption mechanism.

Dual fuel engines fueled with three gaseous and biodiesel fuel combinations

Abstract: Alternative fuels have numerous advantages over fossil fuels as they are renewable, biodegradable, provide energy security and foreign exchange savings, and help in addressing environmental concern...

Facile green synthesis of fluorescent carbon quantum dots from citrus lemon juice for live cell imaging

Abstract: Facile and green one pot hydrothermal method was used for synthesis of fluorescent carbon quantum dots (CQDs) using citrus lemon juice as precursor. The synthesized CQDs were characterized using UV–Vis spectrophotometer, fluorescence spectrometer, transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared spectrometer (FTIR), field emission scanning electron microscope equiped with energy dispersive X-ray spectroscopy (FESEM-EDS) and fluorescence microscopy. The obtained CQDs have high photoluminescence of 10.20% quantum yield. The photoluminescence intensity of CQDs depends on pH of the solution and maximum intensity obtained at pH of 6. The particle size of the carbon dots were distributed in narrow range of 2–10 nm with an average of 5.8 nm. The highly water soluble CQDs have high cell viability even at high concentration which rich up to 85%. MTT assay was used to investigate the potential application of CQDs and the results indicated that the material can be used as florescent probe in the cell imaging.

Preparation and properties of nanopolymer advanced composites: A review

Abstract: The growing demand for continuous improvement in the engineering applications of thermoplastic and thermoset polymer materials compared with metals in various applications led to the materialization of nanopolymer composites by the addition of different nanofillers, with advanced properties. Nanotechnology is assumed as the important technology in the current century. Nanofillers such as nanoclay, carbon nanotubes, carbon black, silica, nanooxides, and metal particles are being used as additives in polymers for decades. The increasing stringent environmental legislation and consumer awareness are highlighted and the importance of synthetic fiber, natural fiber, and thermoplastics are discussed. This chapter is designed to be a comprehensive source of recent literature and study on nanofillers in polymers such as epoxy, polyester, polyethylene terephthalate, polypropylene, high-density polyethylene, and polyvinyl chloride. It has different classes and modification of polymers by nanoparticles. This chapter determines the current status of nanotechnology in the polymer that guides the future studies in this attractive field.

Genetic diversity and symbiotic effectiveness of Bradyrhizobium strains nodulating selected annual grain legumes growing in Ethiopia.

Abstract: Vigna unguiculata, Vigna radiata and Arachis hypogaea growing in Ethiopia are nodulated by a genetically diverse group of Bradyrhizobium strains. To determine the genetic identity and symbiotic effectiveness of these bacteria, a collection of 36 test strains originating from the root nodules of the three hosts was investigated using multilocus sequence analyses (MLSA) of core genes including 16S rRNA, recA, glnII, gyrB, atpD and dnaK. Sequence analysis of nodA and nifH genes along with tests for symbiotic effectiveness using δ15N analysis were also carried out. The phylogenetic trees derived from the MLSA grouped most test strains into four well-supported distinct positions designated as genospecies I-IV. The maximum likelihood (ML) tree that was constructed based on the nodA gene sequences separated the entire test strains into two lineages, where the majority of the test strains were clustered on one of a well-supported large branch that comprise Bradyrhizobium species from the tropics. This clearly suggested the monophyletic origin of the nodA genes within the bradyrhizobia of tropical origin. The δ15N-based symbiotic effectiveness test of seven selected strains revealed that strains GN100 (δ15N=0.73) and GN102 (δ15N=0.79) were highly effective nitrogen fixers when inoculated to cowpea, thus can be considered as inoculants in cowpea production. It was concluded that Ethiopian soils are a hotspot for rhizobial diversity. This calls for further research to unravel as yet unknown bradyrhizobia nodulating legume host species growing in the country. In this respect, prospective research should also address the mechanisms of symbiotic specificity that could lead to high nitrogen fixation in target legumes.

Calibration and validation of SWAT model using stream flow and sediment load for Mojo watershed, Ethiopia

Abstract: The main aim of this study was to setup and evaluate the applicability of physically based soil and water assessment tool (SWAT) model with ArcGIS version 9.3 in assessing the runoff and sediment load from Mojo watershed having a total area of 2017.21 km2 situated in central Oromia Regional state, Ethiopia. In this study for stream flow simulation parameters involving surface runoff (CN2.mgt) and ground water (ALPHA_BNK.rte) are found the most sensitive parameter and the parameters representing channel process (SPCON.bsn, SPEXP.bsn &ADJ_PKP.bsn), geomorphology (SLSUBBSN.hru) and surface runoff (CN2.mgt, & HRU_SLP.hru), were found more sensitive for sediment load simulation. There are a good agreement between the observed and simulated discharge, which was verified using both graphical technique and quantitative statistics. The value of R 2 = 0.75, NSE = 0.76, RSR = 0.49 and PBIAS = 10.9 obtained during calibration and R 2 value 0.71, NSE value 0.70, RSR value 0.59 and PBIAS 9.5 obtained during validation as well as the uniformly scatter points along the 1:1 line during calibration and validation justify that the model is good in simulating runoff from Mojo watershed. For sediment load the computed statistical indicators R 2 = 0.77, NSE = 0.76, RSR = 0.49 and PBIAS = 48.70 were obtained during calibration and during validation the computed statistical indicators were found 0.67 for R 2, 0.65 for NSE, 0.59 for RSR and 50.5 for PBIAS. From the calibration and validation result, it can be concluded that the calibrated parameter values of SWAT model can be used for hydrologic simulation of the un-gauged watershed that is having the similar agro-climatic condition.

Numerical simulation and experimental investigation on static behavior of cold formed steel beam with trapezoidally corrugated web by varying depth-thickness ratio

Abstract: This paper presents a numerical simulation and experimental investigation on the static behavior of cold-formed steel beams with trapezoidally corrugated web has been carried out to find its structural performance of simply supported beam under pure bending. The steel beams with corrugated steel webs represent a new innovative which has emerged in the past decade for short- and medium-span beams. The thin corrugated web affords a significant weight reduction of these beams, compared with hot-rolled beams. In the initial solution, the flanges are made of flat plates, welded to the trapezoidal web sheet, requiring a specific welding technology. The connecting between flanges to the web can be done by means of intermittent welding. The paper summarizes the experimental and numerical investigations carried out at the Hindustan University and, at the end, presents the flexural behavior of cold-formed steel beams with trapezoidally corrugated web. To find the effect of web corrugation, 12 experiments were conducted on cold-formed steel beams. Beams having two different web depth-thickness (dw/tw) ratio 60 and 80 and with three types of web corrugation angles 0°, 30° and 45° were tested. Two beams were tested in each series. The static performance of the three different corrugation angles, including failure mode, load–deflection curves, strength capacity, load–strain curves, moment–curvature curves, flexural stiffness and ductility, are compared and discussed in detail based on the experimental results. Finally, numerical analysis using ANSYS Workbench results are analyzed and the experimental results were validated with the results obtained from the finite element analysis.

Impact of Population Growth on Economic Growth in Africa: A Dynamic Panel Data Approach (1980 -2015)

Abstract: This study examines the impact of population growth on the economic growth of African countries using panel data approach from 1980 -2015. The impact of population growth on economic growth is still largely controversial at national and regional levels. The study used annual secondary data of fifty three (53) African countries sourced from the World Development Indicators database. Data were collected for economic growth, proxied by GDP, population growth, fertility rate, crude death rate and inflation rate. The data were analyzed using descriptive statistics, as well as dynamic panel models of difference and system GMM. The results of the difference and system GMM suggest that population growth exerts a positive impact on economic growth of Africa while fertility has a negative impact on economic growth of Africa. The paper concludes and recommends that population growth impacts positively on economic growth and thus African countries should adopt and implement pragmatic policy measures that will enhance the productivity of its population so as to reap more demographic dividends.

Approximate l-States Solutions to the Schrodinger Equation with Manning-Rosen plus Hellmann Potential via WKB Approximation Scheme

Abstract: The approximate analytical solutions of the radial Schrodinger equation have been obtained by the interaction of Manning-Rosen and Hellmann potentials which is a newly proposed potential. Using the Wentzel-Kramers-Brillouin WKB approach, we obtained the eigenstates solutions for any arbitrary angular momentum. Special cases of potential consideration have been discussed. Eigenenergy solutions to equations obtained play an important role in quantum mechanics because they contain a wealth of vital information regarding the system under consideration.

Optimization of an artificial-recharge–pumping system for water supply in the Maghaway Valley, Cebu, Philippines

Abstract: A coupled simulation-optimization approach to optimize an artificial-recharge–pumping system for the water supply in the Maghaway Valley, Cebu, Philippines, is presented. The objective is to maximize the total pumping rate through a system of artificial recharge and pumping while meeting constraints such as groundwater-level drawdown and bounds on pumping rates at each well. The simulation models were coupled with groundwater management optimization to maximize production rates. Under steady-state natural conditions, the significant inflow to the aquifer comes from river leakage, whereas the natural discharge is mainly the subsurface outflow to the downstream area. Results from the steady artificial-recharge–pumping simulation model show that artificial recharge is about 20,587 m3/day and accounts for 77% of total inflow. Under transient artificial-recharge–pumping conditions, artificial recharge varies between 14,000 and 20,000 m3/day depending on the wet and dry seasons, respectively. The steady-state optimisation results show that the total optimal abstraction rate is 37,545 m3/day and artificial recharge is increased to 29,313 m3/day. The transient optimization results show that the average total optimal pumping rate is 36,969 m3/day for the current weir height. The transient optimization results for an increase in weir height by 1 and 2 m show that the average total optimal pumping rates are increased to 38,768 and 40,463 m3/day, respectively. It is concluded that the increase in the height of the weir can significantly increase the artificial recharge rate and production rate in Maghaway Valley.

Zircon Trace Element Constraints on the Evolution of the Paleoproterozoic Birimian Granitoids of the West African Craton (Ghana)

Abstract: The Paleoproterozoic Birimian granitoids of the West African Craton (WAC) in the northwestern part of Ghana, have been studied for their zircon trace elements concentrations to infer the source characteristics, origin, and magmatic evolution. The zircons in the granitoids have Th/U ratios ranging from 0.03 to 1.55, and display depleted light rare earth elements (LREE) and enriched heavy rare earth elements (HREE) contents, characterized by pronounced positive to negative anomalies of Eu (Eu/Eu*=0.14–0.98 and 1.01–6.06, respectively) and Ce (Ce/Ce*=0.08–0.98 and 1.02–116, respectively), which may imply that they were derived from both magmatic and hydrothermal sources. The geochemical plots of U/Yb vs. Y and Hf, the positive correlation between Hf and the other high field strength elements (HFSE) and high rare earth elements (REE) contents, with enrichment in Ce and depletion in Eu, indicate that the granitoids possibly formed from partial melting of the crust. The trace elements characteristics (i.e., wide range of Hf, Ce/Ce*, Th/U and Zr/Hf values) of the zircons suggest that crystallization of the magma occurred under variable oxidation states, which spanned over a longer period, implying that our data corroborate interpretations from studies of whole-rock geochemistry and geochronology on the granitoids of northwestern Ghana. This further indicates that the evolution of the Birimian granitoids in this part of the WAC occurred earlier than what had been reported in the literature.