Showing papers by "Adama University published in 2019"

A Review on Conducting Polymers-Based Composites for Energy Storage Application

Abstract: Conducting polymers (CPs) have been gathering a great interest in academia and industry by providing the opportunity of combining the electrical properties of a semiconductor and metals with the traditional advantages of conventional polymers such as easy and low cost preparation and fabrication. In this review we examined the conducting polymers-based composites for supercapacitor and batteries, such as conducting polymer-based binary, ternary, and quaternary composites. For their applications in energy storage field, we critically review the development of their applications and the general design rules for energy storage devices including supercapacitors, lithium and other -ions batteries, and their current limitations and future potential to advance energy storage technologies. It is expected that this review will help to improve the knowledge about this conducting polymer and consequently lead to new research fields.

Green synthesis of zinc oxide nanostructures and investigation of their photocatalytic and bactericidal applications

Abstract: We report a facile one-pot green synthesis of zinc oxide (ZnO) nanostructures using aqueous leaf extract of Dolichos Lablab L. as the reducing and capping agent. The optical properties, structure and morphology of the as-synthesized ZnO nanostructures have been characterized by UV-Visible spectroscopy (UV-Vis), Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM) supported with energy dispersive X-ray spectroscopy (EDX), and transmission electron microscopy (TEM). TEM analysis revealed that the as-synthesized ZnO nanostructures have an average particle diameter of 29 nm. XRD patterns confirmed the formation of phase-pure ZnO nanostructures with a hexagonal wurtzite structure. The synthesized ZnO nanostructures were used as a catalyst in the photodegradation of methylene blue (MB), rhodamine B (RhB) and orange II (OII) under visible and near-UV irradiation. The results showed the highest efficiency of photodegradation of ZnO nanostructures for MB (80%), RhB (95%) and OII (66%) at pH values of 11, 9 and 5, respectively, in a 210 min time interval. In addition, the antimicrobial activity of the ZnO nanostructures using the agar well diffusion method against Bacillus pumilus and Sphingomonas paucimobilis showed the highest zones of inhibition of 18 mm and 20 mm, respectively. Hence, ZnO nanostructures have the potential to be used as a photocatalyst and bactericidal component.

Synthesis of visible light responsive iodine-doped mesoporous TiO2 by using biological renewable lignin as template for degradation of toxic organic pollutants

Abstract: The visible light responsive I-doped mesoporous TiO2 (I/TiO2-T) catalysts were synthesized by facile hydrolysis method with lignin as a template. The resulting I/TiO2-T catalysts synthesized from different amounts of I as a dopant and lignin as a template were characterized by X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), transmission electron microscopy (TEM), UV–vis diffuse spectroscopy (DRS), Fourier transform infrared spectroscopy (FTIR), photoluminescence (PL), and electrochemical impedance spectroscopy (EIS). The photocatalytic activities of the resulting catalysts were investigated by the degradation of p-chlorophenol under artificial visible light irradiation. The results showed that the lignin-templated TiO2 with a suitable amount of I-doping (I/TiO2-T) had higher catalytic activity than the catalyst prepared form I-doped TiO2 without lignin template (I/TiO2). Complete degradation of p-chlorophenol was achieved by I/TiO2-T with suitable amount of I-doping at 60 min. However, 95.7, 10.7, and 5.5% of the p-chlorophenol was degraded with I/TiO2, TiO2-T, and P25 catalysts, respectively, under 140 min visible light irradiation. The enhanced catalytic activities of the samples with template and I-doping may be due to the small grain size and high specific surface area of the catalysts. The band gap and the electrical properties of TiO2 also could be adjusted with I-doping. The I-doped TiO2 with the extrinsic I5+-to-Ti4+ and the iodine-to-oxygen donor defects could be excited by visible irradiation for efficient pollutants degradation. A possible photocatalytic mechanism for the degradation of the pollutants with I/TiO2-T under visible light irradiation was also proposed.

Evaluation of bi-functional applications of ZnO nanoparticles prepared by green and chemical methods

Abstract: We report the chemical synthesis and green synthesis of zinc oxide nanoparticles (ZnO NPs) by using the leaf extract of the plant Ruta chalepensis. In addition, a comparative evaluation of photochemical and electrochemical properties of green ZnO (g-ZnO) and chemical ZnO (c-ZnO) NPs has been presented in this paper. The g-ZnO and c-ZnO NPs were found to exhibit uniform particle size distribution with an average diameter of 17.72 nm and 25.0 nm, respectively. These NPs possess hexagonal phase with wurtzite structure which is revealed by PXRD results. The SEM studies revealed a more uniform and flower like morphology for the g-ZnO NPs. The UV-DRS studies revealed the band energy gaps (Eg) of 2.86 eV and 3.35 eV for g-ZnO and c-ZnO NPs, respectively. The degradation studies were carried out for three dyes, Malachite Blue (MB), Indigo Carmine (IC) and Malachite Green (MG). g-ZnO NPs exhibited highest photocatalytic activity for Malachite Green (MG) under UV light irradiation (from 0 to 60 min), when compared to c-ZnO NPs. Electrochemical studies have been carried out for both ZnO NPs in 1 M KOH solution. Cyclic voltammetric (CV) results showed higher electrode reversibility for g-ZnO NPs. The superior behavior observed for g-ZnO NPs can be attributed to its lower charge transfer resistance as confirmed by electrochemical impedance spectroscopy (EIS) study. The results also prove that g-ZnO NPs would be a better alternative photocatalyst for waste water treatment.

Fabrication of novel 1D/2D V2O5/g-C3N4 composites as Z-scheme photocatalysts for CR degradation and Cr (VI) reduction under sunlight irradiation

Abstract: Photocatalytic materials for environmental remediation of organic pollutants and heavy metals require not only a strong visible light response and high photocatalytic performance, but also the regeneration and reuse of catalysts. In this work, 1D/2D V2O5 nanorods/g-C3N4 nanosheets (VONRs/CNNs) composites were prepared by a facile impregnation method and employed in the degradation of a Congo red (CR) and reduction of Cr (VI) under sunlight irradiation. The as-prepared samples were studied by several characterization techniques including XRD, SEM, TEM, EDS, XPS, FTIR, UV–vis DRS and PL. Results revealed that the interface interaction between VONRs and CNNs was recognized via V2O5 nanorods loading on the surface of g-C3N4 nanosheets, improving the separation and transfer of photogenerated electron-hole pairs and restraining the recombination rate of charge carriers. As a result, the photocatalytic activity of the composites was enhanced in comparison with pure CNNs and VONRs. The photocatalytic efficiency of optimal composite (4-VONRs/CNNs) for the removal of CR (Cr (VI)) was about 9.33 (4.22) and 73.52 (19.2) times higher than that of pure CNNs and VONRs, respectively. Meanwhile, the 4-VONRs/CNNs exhibited good photocatalytic stability in recycling experiments. Such enormous enhancement in photocatalytic performance was predominantly ascribed to the efficient separation and transfer of photogenerated electron-hole pairs at the VONRs/CNNs interface imparted through the direct Z-scheme charge carrier migration mechanism. Moreover, the energy band structure and the quenching effects of different scavengers demonstrated that the electrons of CNNs and holes of VONRs with higher oxidizability and reducibility are the real participants in photocatalytic reactions.

Synthesis and photocatalytic activities of a CuO/TiO2 composite catalyst using aquatic plants with accumulated copper as a template

Abstract: A CuO/TiO2 composite photocatalyst was synthesized by using a hydrolysis method. In the synthesis of the CuO/TiO2 composite catalyst, the aquatic plant Eichhornia crassipes containing accumulated copper was used and combined with titanium chloride precursor. X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV-Vis diffuse spectroscopy (DRS), and N2 adsorption–desorption isotherms were used for CuO/TiO2 characterization. The results showed that the CuO/TiO2 synthesized with Eichhornia crassipes as a template had smaller crystallite size (12.6 nm), higher specific surface area (109 m2 g−1), and higher pore volume (0.135 cm3 g−1). The catalytic activity of the CuO/TiO2 composite catalyst was also investigated by the degradation of phenol under ultraviolet (UV) and visible light irradiation, showing excellent catalytic activity. Complete removal of phenol was achieved at 80 and 120 min under UV and visible light sources, respectively. The catalytic performances may be due to the higher porosity and surface area of the composite catalyst. The Eichhornia crassipes aquatic plant also controls the crystal growth and prevents aggregation, which could enhance the catalytic activity. Moreover, the formation of the p–n CuO/TiO2 heterojunction also facilitates the separation of electrons and holes, and improves the photocatalytic activity of the material.

A noble bimetal oxysulfide CuVOS catalyst for highly efficient catalytic reduction of 4-nitrophenol and organic dyes

Abstract: A novel copper–vanadium bimetallic oxysulfide (CuVOS) nanoparticle catalyst was successfully synthesized by a facile method. The samples were characterized by X-ray photoelectron spectrometry (XPS), X-ray diffractometry (XRD), field-emission scanning electron microscopy (FE-SEM), UV-Vis diffuse spectroscopy (DRS), Fourier transform infrared spectroscopy (FTIR), and N2 adsorption–desorption isotherms. In order to check the catalytic efficiencies toward reduction reaction, 4-nitrophenol (4-NP) and other organic dyes such as rhodamine-B (RhB), methylene blue (MB), and methyl orange (MO) were used. The results showed that the CuVOS prepared in the presence of a suitable amount of N2H4 during the synthesis of the nanoparticles exhibited the fastest reduction capabilities by using NaBH4 as a reducing agent. It was demonstrated that a 100 mL 4-NP (20 ppm) solution was completely reduced by 5 mg CuVOS-3 within 2 min. Moreover, the complete reduction of 100 mL of MO, RhB, and MB solutions of 100 ppm was also achieved by 5 mg CuVOS-3 within 2 min, 6 min, and 5 min, respectively. Hence, the CuVOS is an efficient catalyst for reducing 4-NP and organic dyes and can have great potential for industrial application.

Aborted propagation of the Ethiopian rift caused by linkage with the Kenyan rift.

Abstract: Continental rift systems form by propagation of isolated rift segments that interact, and eventually evolve into continuous zones of deformation. This process impacts many aspects of rifting including rift morphology at breakup, and eventual ocean-ridge segmentation. Yet, rift segment growth and interaction remain enigmatic. Here we present geological data from the poorly documented Ririba rift (South Ethiopia) that reveals how two major sectors of the East African rift, the Kenyan and Ethiopian rifts, interact. We show that the Ririba rift formed from the southward propagation of the Ethiopian rift during the Pliocene but this propagation was short-lived and aborted close to the Pliocene-Pleistocene boundary. Seismicity data support the abandonment of laterally offset, overlapping tips of the Ethiopian and Kenyan rifts. Integration with new numerical models indicates that rift abandonment resulted from progressive focusing of the tectonic and magmatic activity into an oblique, throughgoing rift zone of near pure extension directly connecting the rift sectors.

Synthesis of Sn-WO3/g-C3N4 composites with surface activated oxygen for visible light degradation of dyes

Abstract: Sn-WO3/g-C3N4 composites were synthesized by calcination method. The materials were characterized with different techniques and photocatalytic activities examined by the degradation of anionic methyl orange (MO) and cationic Rhodamine B (RhB) under visible light. 8% Sn-WO3/g-C3N4 showed superior degradation efficiency with 87% MO and 99% RhB dye removal within 120 and 50 min of irradiation time, respectively. X-ray photoelectron spectroscopy (XPS) analysis reveals molecular oxygen adsorption on the surface of the as-prepared composite material. The introduction of tin in Sn-WO3 solid solution with a high atomic Sn:W ratio of 1:2 and the construction of interfacial hetrojunction with graphitic carbon nitride (g-C3N4) plays a vital role to enhance the photocatalytic activity of the as-prepared composites by activating oxygen to react with dye molecules.

Sorption behaviour of bamboo fibre reinforced composites, why do they retain their properties?

Abstract: The influence of moisture on the mechanical properties of bamboo fibre reinforced composites was assessed both for static and hygroscopic cyclic conditioning. Static conditioning revealed that bamboo fibre reinforced composites show a smaller decrease in Young’s modulus with moisture content than other natural fibre reinforced composites such as for example flax based composites. The behaviour is explained by the chemical composition of the fibre and demonstrated by dynamic mechanical analysis that illustrates how composites made with fibres of high lignin content retain their glass transition temperature in moist conditions. The influence of hygroscopic cycling was also assessed, with emphasis on the influence of the remaining parenchyma on the fibre surface. Clean fibres, are beneficial for the long term behaviour, with less deterioration in properties. Porosity analysis was performed via X-ray computed tomography to provide insight into the material structure of the composite and the effects of hygroscopic cycling.

Antibacterial Activity of Coumarins and Carbazole Alkaloid from Roots of Clausena anisata.

Abstract: Clausena anisata is one of the medicinal plants used traditionally for treatment of parasitic infections, irritation (boils, ringworm, and eczema), flatworm infestations, influenza, abdominal cramps, and constipation. Phytochemical screening test of dichloromethane/methanol (1 : 1) roots extract revealed the presence of flavonoids, phytosterols, coumarins, phenols, alkaloids, tannins, terpenoids, and free reducing sugars and the absence of saponins. Silica gel column chromatographic separation of the dichloromethane/methanol (1 : 1) extract afforded a carbazole alkaloid derivative of heptazoline (1) and three coumarins (2–4), including the known coumarins imperatorin (3) and chalepin (4). Structures of the compounds were elucidated by spectroscopic techniques (IR, 1H NMR, 13C NMR, and DEPT-135). Antibacterial activity of the crude extracts and isolated compounds was screened using agar diffusion method against strains of Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, and Bacillus substilis. The results of antibacterial test revealed derivative of heptaphylline (1) and imperatorin (3) exhibited comparable antibacterial activity against S. aureus and B. substilis (14 and 13 mm zone of inhibition, respectively) to that of ciprofloxacin (15 mm zone of inhibition) at a concentration of 20 µg/mL. Chalepin (4) revealed more antibacterial activity against B. substilis (16 mm zone of inhibition) compared to ciprofloxacin (15 mm).

An Improved C4.5 Data Mining Driven Algorithm for the Diagnosis of Coronary Artery Disease

Abstract: Coronary artery disease (CAD) is one of the deadly diseases in the world, especially in developed countries. This disease is not epidemic but it re-mains the single most common cause of death. This research used an im-proved C4.5 data mining algorithm for the diagnosis of CAD. A performance evaluation of the improved algorithm was carried out against the traditional C4.5 Algorithm. Consequently, the improved C4.5 data mining algorithm has shown better performance with an overall accuracy of 97.23 %, 97.03 % specificity, and 96.39% of sensitivity. The improved algorithm built a tree with twenty-seven leaves and forty-seven sizes, which can be converted into the production rules for knowledge base of expert system to diagnose CAD. This helps in addressing the problematic bottleneck of knowledge acquisition process in expert system for diagnosis of CAD.

MASCA–PSO based LLRBFNN model and improved fast and robust FCM algorithm for detection and classification of brain tumor from MR image

Abstract: A novel modified adaptive sine cosine optimization algorithm (MASCA) integrated with particle swarm optimization (PSO) based local linear radial basis function neural network (LLRBFNN) model has been proposed for automatic brain tumor detection and classification. In the process of segmentation, the fuzzy C means algorithm based techniques drastically fails to remove noise from the magnetic resonance images. So, for reduction of noise and smoothening of brain tumor magnetic resonance image an improved fast and robust fuzzy c means algorithm segmentation algorithm has been proposed in this research work. The gray level co-occurrence matrix technique has been employed to extract features from brain tumor magnetic resonance images and the extracted features are fed as input to the proposed modified ASCA–PSO based LLRBFNN model for classification of benign and malignant tumors. In this research work the LLRBFNN model’s weights are optimized by using proposed MASCA–PSO algorithm which provides a unique solution to get rid of the hectic task of radiologist from manual detection. The classification accuracy results obtained from sine cosine optimization algorithm, PSO and adaptive sine cosine optimization algorithm integrated with particle swarm optimization based LLRBFNN models are compared with the proposed MASCA–PSO based LLRBFNN model. It is observed that the result obtained from the proposed model shows better classification accuracy results as compared to the other LLRBFNN based models.

Effects of Azadirachta Indica Leaf Extract, Capping Agents, on the Synthesis of Pure And Cu Doped ZnO-Nanoparticles: A Green Approach and Microbial Activity

Abstract: Abstract The current studies presented the green synthesis of zinc oxide and copper doped ZnO nanoparticles (NPs) using different ratios of Neem leaf extract and its antibacterial application on drug-resistant bacteria. The synthesized NPs were characterized using: X-ray diffractions (XRD), Fourier Transform Infrared Spectroscopy (FT-IR), Scanning Electron Microscope (SEM), UV–visible spectroscopy and a simultaneous DTA-TGA thermal analyzer. All the synthesized materials were stable above 400°C. The powder diffraction studies indicated the formation of phase pure materials with wurtzite structure for pure ZnO and 0.5%, 1%, 1.5% Cu doped ZnO with the crystallite size in the range of 16.07 – 23.74 nm. SEM analysis revealed the formation of spherical shaped NPs with large grain size for 10% (v/v) ratio of aqueous leave extract. The aqueous extract of neem act as capping agent and prevent the NPs from agglomeration. The spectral studies confirmed the formation of NPs with the absorbance peak that is different from the micro-size ZnO. The antibacterial activities of the synthesized materials ZnO (1:1) against Staphylococcus aureus and uncalcined ZnO (7:3) and (Zn0.985Cu0.015O) against Bacillus subtilis were enhanced when referenced to the standard gentamicin. Graphical Abstract

A retrospective analysis on the transmission of Plasmodium falciparum and Plasmodium vivax: the case of Adama City, East Shoa Zone, Oromia, Ethiopia.

Abstract: Malaria is more often considered a problem of the rural poor and the disease has been overlooked in urban settings for centuries due to the assumption that economic development in urban areas results in better life conditions, such as improved housing, drainage system and environmental changes that makes urban areas not conducive for breeding of the malaria vector. But, for many African countries, including Ethiopia, in most urban areas, although there are rapid developments, they are characterized by poor housing, lack of sanitation and drainage of surface water that would provide favourable conditions for vector breeding. Limited studies have been conducted as far as urban malaria is concerned in Ethiopia. The purpose of this study was to assess the status of falciparum and vivax malaria transmission in Adama City, Eastern Shoa Zone, Oromia, Ethiopia. Understanding the local epidemiology of malaria will help policy makers and other stakeholders to design and implement tailored cost effective and efficient intervention strategies targeting urban malaria. The study was designed to analyse 5-year trends of malaria burden by two co-endemic species in Ethiopia (Plasmodium falciparum and Plasmodium vivax) and its annual and seasonal transmission pattern in the city, by using retrospective data on malaria burden by species, malaria related inpatient department (IPD) and outpatient department (OPD) consultations from 2013/14 to 2017/18. OPD retrospective data analysis indicated that adolescents and adults (≥ 15 years of age) were most affected by P. vivax 43.5% (2986/6862) and P. falciparum 31.7% (2179/6862). Plasmodium vivax was found to be a predominant species in causing malaria burden in the city exhibiting less seasonal occurrence, and the relative burden of P. vivax is gradually increasing from year to year over P. falciparum. Malaria is endemic to the city showing a public health problem. The productive group of the community, adolescents and adults, were most affected exacerbating poverty. Plasmodium vivax was found to be the highest malaria burden in the city and the observed epidemiological shift from P. falciparum to P. vivax calls for additional tailored intervention strategies to reduce the associated burden.

An Effective Approach to Input Variable Selection for Preliminary Cost Estimation of Construction Projects

Abstract: Accurate cost estimates are vital to the effective realisation of construction projects. Extended knowledge, wide-ranging information, substantial expertise, and continuous improvement are required to attain accurate cost estimation. Cost estimation at the preliminary phase of the project is always a challenge as only limited information is available. Hence, rational selection of input variables for preliminary cost estimation could be imperative. A systematic input variable selection approach for preliminary estimating using an integrated methodology of factor analysis and fuzzy AHP is presented in this paper. First, the factor analysis is used to classify and reduce the input variables and their variable coefficients are determined. Second, fuzzy AHP based on the geometric mean method is employed to determine the weights of input variables in a fuzzy environment where the subjectivity and vagueness are handled with natural language expressions parameterized by triangular fuzzy numbers. Then, the input variables are suggested to be selected starting with those having high coefficient and high importance weight. A set of three variables, one from each group, can be added to the estimating model at a time so that the problem of collinearity can vanish and good accuracy of the estimate can be ensured. The proposed approach enables cost estimators to better understand the complete input variable selection process at the early stage of project development and provide a more accurate, rational, and systematic decision support tool.

Impacts of climate change on stream flow and water availability in Anger sub-basin, Nile Basin of Ethiopia

Abstract: This study focused on analysis of response of stream flow and water availability that may happen due to climate change in the case of Anger sub-basin (8001.28 km2) in the southern part of the Upper Blue Nile River Basin. A single GCM from Coupled Model Inter-comparison Project Phase 5 with single regional climate model and delta change bias correction approaches combined with SWAT hydrological model were used to project stream flow for the developed scenario over the study periods of 2020s and 2080s including the current conditions. The result indicates that inconsistent increasing or decreasing of water availability was observed. The total annual surface water resource potential of Anger sub-basin estimated at the base period according to this study was about 3.396 BCM/year at current situations. However, the future scenarios in 2020s increasing water availability are shown by 2.71% for RCP 4.5 and negligible decrement shown by 0.14% for RCP 8.5 scenarios. As well as decreasing of water resource was shown by 7.43% and 11.3% at 2080s for both RCP 4.5 and RCP 8.5 scenarios, respectively. This is indicative of the likely future response of stream flow of the study area.