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Showing papers by "Adama University published in 2020"


Journal ArticleDOI
TL;DR: This review presents a detailed discussion of the antibacterial activity improvement of ZnO by forming a composite, doping, and optimizing different conditions and supports for developing a satisfactory mechanism.
Abstract: Metal oxide nanomaterials are one of the preferences as antibacterial active materials. Due to its distinctive electronic configuration and suitable properties, ZnO is one of the novel antibacterial active materials. Nowadays, researchers are making a serious effort to improve the antibacterial activities of ZnO by forming a composite with the same/different bandgap semiconductor materials and doping of ions. Applying capping agents such as polymers and plant extract that control the morphology and size of the nanomaterials and optimizing different conditions also enhance the antibacterial activity. Forming a nanocomposite and doping reduces the electron/hole recombination, increases the surface area to volume ratio, and also improves the stability towards dissolution and corrosion. The release of antimicrobial ions, electrostatic interaction, reactive oxygen species (ROS) generations are the crucial antibacterial activity mechanism. This review also presents a detailed discussion of the antibacterial activity improvement of ZnO by forming a composite, doping, and optimizing different conditions. The morphological analysis using scanning electron microscopy, field emission-scanning electron microscopy, field-emission transmission electron microscopy, fluorescence microscopy, and confocal microscopy can confirm the antibacterial activity and also supports for developing a satisfactory mechanism. Graphical abstract showing the metal oxides antibacterial mechanism and the fluorescence and scanning electron microscopic images.

148 citations


Journal ArticleDOI
TL;DR: Various selected quinolines and derivatives with potential biological and pharmaceutical activities will be presented and synthesis protocols used up to now for the construction of the principal quinoline scaffold are highlighted.
Abstract: Recently, quinoline has become an essential heterocyclic compound due to its versatile applications in the fields of industrial and synthetic organic chemistry. It is a vital scaffold for leads in drug discovery and plays a major role in the field of medicinal chemistry. Nowadays there are plenty of articles reporting syntheses of the main scaffold and its functionalization for biological and pharmaceutical activities. So far, a wide range of synthesis protocols have been reported in the literature for the construction of this scaffold. For example, Gould–Jacob, Friedlander, Pfitzinger, Skraup, Doebner–von Miller and Conrad–Limpach are well-known classical synthesis protocols used up to now for the construction of the principal quinoline scaffold. Transition metal catalysed reactions, metal-free ionic liquid mediated reactions, ultrasound irradiation reactions and green reaction protocols are also useful for the construction and functionalization of this compound. The main part of this review focuses on and highlights the above-mentioned synthesis procedures and findings to tackle the drawbacks of the syntheses and side effects on the environment. Furthermore, various selected quinolines and derivatives with potential biological and pharmaceutical activities will be presented.

105 citations


Journal ArticleDOI
21 Jul 2020
TL;DR: Cloud computing, IoT sensors, wireless technology and UAVs are combined for the purpose of fire detection in this paper to improve the accuracy of the system and rules are formulated such that the true detection rate is improved.
Abstract: Smart cities with smart infrastructure is a rapidly flourishing field of research in the modern days. Open areas, agricultural land, forests, office, homes and several areas can have occurrences of fire accidents leading to loss of significant resources. Unmanned Aerial Vehicle (UAV) and wireless sensor network technologies are used fir detection of fire at an early stage in this paper. This helps in avoiding serious fire accidents. The environmental parameters are monitored using the sensor architecture. The sensors uses IoT based applications for processing the gathered environmental data. Cloud computing, IoT sensors, wireless technology and UAVs are combined for the purpose of fire detection in this paper. In order to improve the accuracy of the system, integration of image processing schemes is done in this system. The rules are formulated such that the true detection rate is improved. The existing state-of-the-art models are compared with the proposed system. The simulation results show that the rate of fire detection of the proposed system is improved for up to 98% when compared to the traditional models.

104 citations


Journal ArticleDOI
TL;DR: In this article, the synergistic influence of phytoconstituents in green copper nanoparticles (g-Cu NPs) was investigated for the enhancement of antimicrobial properties of NPs.
Abstract: Indigenous medicinal plant of Ethiopia has been applied for the first time to investigate the synergistic influence of phytoconstituents in green copper nanoparticles (g-Cu NPs) towards the enhancement of antimicrobial properties of NPs. We report the green synthesis of Cu NPs using Hagenia abyssinica (Brace) JF. Gmel. leaf extract. The synthesized g-Cu NPs were characterized by UV-visible, UV-DRS, FT-IR, XRD, SEM, EDXA, TEM, HRTEM, and SAED techniques. The maximum absorbance, , was found to be 403 nm for g-Cu NPs due to surface plasmon resonance. The energy gap, of NPs, was found to be 2.19 eV. FTIR spectra confirmed the presence of polyphenols, tannins, and glycosides in the leaf extract of Hagenia abyssinica. The spectral band at 740 cm-1 is a characteristic of interaction between Cu and biomolecules of the extract. The XRD analysis revealed that the g-Cu NPs appears to be more crystalline in nature. SEM and TEM micrographs showed a mix of spherical, hexagonal, triangular, cylindrical, and irregularly shaped Cu particles. The average particle size of NPs was found to be 34.76 nm by ImageJ analysis. EDX analysis confirmed the presence of copper in the g-Cu NPs. In addition, the SAED pattern of g-Cu NPs presented concentric circular patterns for 4 major planes of crystalline copper and its oxides. The experimental and calculated - spacing values of one of the crystal planes (111) were found to be 0.2432 nm and 0.2444 nm, respectively. The - spacing values of 0.2444 nm and 0.2040 nm correspond to d111Cu2O and d111Cu lattice fringes, respectively. The antibacterial test conducted on E. coli, Pseudomonas aeruginosa, Staphylococcus aureus, and Bacillus subtilis showed good zone of inhibitions 12.7, 12.7, 14.7, and 14.2 mm, respectively, proving potentiality of g-Cu NPs as a remedy for infectious diseases caused by tested pathogens.

97 citations


Journal ArticleDOI
TL;DR: The novelty of this work is that the designed supercapacitors showed stable electrochemical performance even at 1000th cycle, which might be useful for rechargeablesupercapacitor applications.
Abstract: This work reveals a green combustion route for the synthesis of TiO2, Fe2O3 and TiO2-Fe2O3 nanocomposites as photocatalysts for decolorization of Titan Yellow (TY) and Methyl Orange (MO) dyes at room temperature in aqueous solution concentration of 20 ppm under UV-light irradiation. We observed that the TiO2-Fe2O3 nanocomposite shows superior photocatalytic activity for TY dye compared to pure TiO2 and Fe2O3. Rate constant (k) values of TiO2, Fe2O3 and TiO2–Fe2O3 for TY and MO are 0.0194, 0.0159, 0.04396 and 0.00931, 0.00772 0.0119 kmin−1 respectively. The surface area and pore volume of TiO2-Fe2O3 nanocomposite were found to be 71.56 m2/g and 0.076 cm3/g, respectively as revealed by BET studies. From the Barrett–Joyner–Halenda (BJH) plot, the mean pore diameter of TiO2-Fe2O3 nanoparticles was found to be 2.43 nm. Further, the TiO2-Fe2O3 nanocomposite showed good electrochemical behavior as an electrode material for supercapacitors when compared to pure TiO2 and Fe2O3 nanoparticles resulted in stable electrochemical performance with nearly 100% coulombic efficiency at a scan rate of 10 mV/s for 1000 cycles. Interestingly, the novelty of this work is that the designed supercapacitors showed stable electrochemical performance even at 1000th cycle, which might be useful for rechargeable supercapacitor applications. The electrochemical properties of the nanocomposites were compared by the data obtained by cyclic voltammograms, charge-discharge tests and electrochemical impedance spectroscopic studies. These results demonstrated that the TiO2-Fe2O3 nanocomposite showed stable performance compared to TiO2 and Fe2O3 nanoparticles at current density of 5 Ag−1.

94 citations


Journal ArticleDOI
TL;DR: In this article, the photocatalytic performance of the synthesized nanocrystalline Ag2O by photocatalysis degradation of organic dyes under visible light irradiation has been discussed thoroughly in a review.
Abstract: Even though the photocatalytic processes are a good technology for treatment of toxic organic pollutants, the majority of current photocatalysts cannot utilize sunlight sufficiently to realize the decomposition of these organic pollutants. As stated by various researchers, metal oxide nanoparticles have a significant photocatalytic performance under visible light source. Among various chemical and physical methods used to synthesize nanostructured silver oxide, green synthetic route is a cheaper and environmental friendly method. To confirm the optimum production of Ag2O NPs, effect of pH, extract concentration, metal ion concentration, and contact time were optimized. The structure, morphology, crystallinity, size, purity, elemental composition, and optical properties of obtained Ag2O NPs were characterized by different techniques, such as scanning electron microscopy (SEM), transmission electron microscope (HRTEM), X-ray diffraction (XRD), energy dispersive spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FT-IR), and UV-visible spectrophotometer accordingly as revealed by our literature review. The photocatalytic performance of the synthesized nanocrystalline Ag2O by photocatalytic degradation of organic dyes under visible light irradiation has been discussed thoroughly in this review. Many past studies revealed that organic dyes and pollutants are decomposed completely by green synthesized Ag2O NPs under irradiation of visible light.

80 citations


Journal ArticleDOI
01 Apr 2020-Heliyon
TL;DR: Relationships among leadership styles, work engagement and work outcomes designated by task performance and innovative work behavior among information and communication technology professionals in two countries: Ethiopia and South Korea showed that transformational leadership style had a significant positive relationship with employees' work engagement And transactional leadership styleHad a significant negative relationship with task performance.

80 citations


Journal ArticleDOI
TL;DR: In this article, a green approach was used to synthesize zinc oxide nanoparticles using Lippia adoensis leaf extract which is an endemic medicinal plant and cultivated in home gardens of different regions of Ethiopia.
Abstract: The synthesis of metal oxide nanoparticles with the use of medicinal plant extract is a promising alternative to the conventional chemical method. This work aimed to synthesize zinc oxide nanoparticles using a green approach from indigenous “Koseret” Lippia adoensis leaf extract which is an endemic medicinal plant and cultivated in home gardens of different regions of Ethiopia. The biosynthesized zinc oxide nanoparticles were characterized using thermogravimetric analysis, X-ray diffraction, scanning electron microscopy-energy dispersive spectroscopy, transmission electron microscopy, ultraviolet-visible spectroscopy, and Fourier transform infrared spectroscopy. Furthermore, this study also evaluated the antibacterial activity of the synthesized ZnO nanoparticles against clinical and standard strains of Escherichia coli, Klebsiella pneumonia, Staphylococcus aureus, and Enterococcus faecalis by the disc diffusion method. According to the result of this study, ZnO nanoparticles synthesized using Lippia adoensis leaf extract showed promising result against both Gram-positive and Gram-negative bacterial strains with a maximum inhibition zone of 14 mm and 12 mm, respectively, using uncalcinated form of the synthesized ZnO nanoparticles.

78 citations


Journal ArticleDOI
TL;DR: In this paper, a series of experiments were designed and conducted to prepare biodiesel from cottonseed oil and to blend it with octanol, and the performance of the engine with the blended fuel was analyzed through characterization and measurement of the gas emissions from the engine.
Abstract: In the present work, a series of experiments were designed and conducted to prepare biodiesel from cottonseed oil and to blend it with octanol. The thermal and mass transfer characteristics of the biodiesel were further improved by adding functionalized multi-walled carbon nanotubes (MWCNTs). The performance of the engine with the blended fuel was analyzed through characterization and measurement of the gas emissions from the engine. Four blends of cottonseed oil (B20, B40, B60, and B100) were prepared initially, and each blend was added with octanol additive of 5%, 10%, and 15% together with 3% of functionalized MWCNTs by mass. The performance analysis showed that B20 with 5%, 10%, and 15% octanol represented relatively lower brake specific fuel consumption relative to all test fuels. Likewise, the addition of MWCNT nanoparticle further stabilized the rate of fuel consumption and brake thermal efficiency. It was also identified that at larger values of diesel and biodiesel blends, the performance and also the quantity of gas emission were the same.

78 citations


Journal ArticleDOI
TL;DR: In this paper, the hazards index value was calculated to estimate the noncarcinogenic risk to adult (male, female) and children suggested by the United States Environmental Protection Agency (USEPA).
Abstract: The main objective of this study was to evaluate the groundwater quality for domestic, agriculture use and to describe fluoride contamination in groundwater and their impacts on human health. 67 groundwater samples were collected and analyzed for major ions. Water Quality Index (WQI), Piper diagram and Gibbs diagrams were calculated to measure the suitability of groundwater for drinking purpose. The hazards index value was calculated to estimate the noncarcinogenic risk to adult (male, female) and children suggested by the United States Environmental Protection Agency (USEPA). The irrigation indices were calculated to evaluate the quality of water for irrigation purpose. Statistical methods such as principal component and hierarchical cluster analysis were used to analyses the inter-relationship of data. Hydrochemistry of the samples shows, the major ions in the order of Ca2+>Mg2+>Na+ and Cl->SO4- in the study area. WQI value of groundwater, 74.62% of sample locations are good and 25.38 % of sample locations need primary treatment for drinking purpose. The results of the hazards index show that 65.67% of the sample locations exceeds the tolerable limit for non-carcinogenic risk (greater than one) for children higher than the risk level for Male and female. Statistical report of PCA and HCA reveals that Ca-Na-HCO3-F has positive loading and TDS-EC has negative loading. The study results show that rock-water interaction and anthropogenic activities are the major factors that influence the quality of groundwater. The continuous intake of excess concentration fluoride causes bone diseases and teeth problems.

72 citations


Journal ArticleDOI
21 Feb 2020
TL;DR: The prepared NCQDs possess high water solubility, high ionic stability, resistance to photobleaching, and bright blue color under ultraviolet radiation with a high quantum yield.
Abstract: In this study, we report a green and economical hydrothermal synthesis of fluorescent-nitrogen-doped carbon quantum dots (NCQDs) using citrus lemon as a carbon source. The prepared NCQDs possess high water solubility, high ionic stability, resistance to photobleaching, and bright blue color under ultraviolet radiation with a high quantum yield (∼31%). High-resolution transmission electron microscopy (HRTEM) results show that the prepared NCQDs have a narrow size distribution (1–6 nm) with an average particle size of 3 nm. The mercury ion (Hg2+) sensing efficiency of the NCQDs was studied, and the result indicated that the material has high sensitivity, high precision, and good selectivity for Hg2+. The limit of detection (LOD) is 5.3 nM and the limit of quantification (LOQ) is 18.3 nM at a 99% confidence level. The cytotoxicity was evaluated using MCF7 cells, and the cell viabilities were determined to be greater than 88% upon the addition of NCQDs over a wide concentration range from 0 to 2 mg/mL. Based ...

Journal ArticleDOI
15 Apr 2020
TL;DR: The aim of the research is to analyze the spatial distribution of COVID-19 and its trends with the help of GIS software and to monitor active ties using GIS spatial analysis to control such as a CO VID-19 virus spreading problem.
Abstract: COVID-19 Coronavirus is now one of the most contagious diseases of the recently discovered and spread across the China in 2019 and has received global attention. In most COVID-19-infected individuals, respiratory symptoms should be mild to moderate and improve without the need for medical care. The risk of serious disease is higher for senior citizens and people with serious health problems, such as heart disease, diabetes, severe respiratory disease, and cancer. The World Health Organization (WHO) has formally declared the outbreak of COVID-19 to be a global pandemic. As on 11 April 2020 in India the largest number of persons testing positive for COVID-19 since the outbreak earlier month with samples of people, mostly contacts of already confirmed patients, rendering positive. In India total confirmed cases 7364, 633 are cured/discharged, with 240 deaths had been reported by the Ministry of Health and Family Welfare Government of India. The aim of the research is to analyze the spatial distribution of COVID-19 and its trends with the help of GIS software. At this time, there are no precise antibiotics or treatment options for COVID-19. Besides, several ongoing clinical studies are assessing effective treatments. The best way to protect and sluggish transmission should be well advised about the current COVID-19 virus, the disease it triggers and also how it continues to spread. Therefore, monitoring active ties using GIS spatial analysis is very important to control such as a COVID-19 virus spreading problem. Article history Received: 10 April 2020 Revised: 12 April 2020 Accepted: 14 April 2020

Journal ArticleDOI
TL;DR: Both Fe3 O4 and silica-coated Fe3O4 NPs demonstrated better antimicrobial activities and were tested against Gram-negative and Gram-positive bacteria.
Abstract: Magnetite and silica-coated magnetite (Fe3O4) nanoparticles (NPs) were synthesized by water-in-oil (W/O) microemulsion method from hydrated ferric nitrate, ferrous sulfate precursors and ammonia a precipitating agent with the assistance of Tween-80 and SDS surfactants. The synthesized materials were characterized by X-ray diffraction, scanning electron microscopy, thermal analyzer, and infrared spectroscopy. X-ray diffraction pattern of Fe3O4 showed that particles were phase pure with a cubic inverse spinel structure and FT-infrared spectra confirmed the presence of Fe-O bond in tetrahedral and octahedral interstitial sites. The crystallite size determined from powder XRD data with Scherer’s equation was in the range of 7.3 ± 0.05 nm–10.83 ± 0.02 nm for uncoated Fe3O4 and 16 ± 0.14 nm for silica-coated Fe3O4 NPs. The SEM micrographs of the uncoated Fe3O4 oxide revealed the agglomeration of the magnetite (Fe3O4) particles. But the silica-coated Fe3O4 oxide exhibited homogeneous distribution of particles with relatively less agglomerate of the particles. The particle size of Fe3O4 NPs slightly increased with the temperature and precursor concentration. The antimicrobial activities of Fe3O4 and silica-coated Fe3O4 nanoparticles were tested against Gram-negative (Escherichia coli and Pseudomonas aeruginosa) and Gram-positive (Staphylococcus aureus and Bacillus subtilis) bacteria. Both Fe3O4 and silica-coated Fe3O4 NPs demonstrated better antimicrobial activities.

Journal ArticleDOI
TL;DR: In this article, a review of different bandgap metal oxides that form a suitable heterojunction with ZnO, depending on the ideas of regeneration, surface area, and stability, is presented.
Abstract: In recent years, the remediation of hazardous organic contaminants using semiconductor metal oxide photocatalyst has taught extensive attention Next to TiO2, ZnO has been well-known as a significant photocatalyst material Due to the formation of different defects, even though photocatalysis using bare ZnO is useful in pollutant remediation, several drawbacks make it less effective In this review, to reduce these drawbacks, forming a heterojunction between different bandgap metal oxides has been assessed Among different metal oxides that form a suitable heterojunction with ZnO, depending on the ideas of regeneration, surface area, and stability; this review focuses on iron oxide and manganese oxide materials Different analytical techniques that confirm the improvement of bare ZnO towards electron-hole recombination, surface area, photo corrosion, and regeneration were also discussed During the adsorption-photocatalysis experiment, to understand the detailed surface reaction information, testing at least some selected adsorption isotherm and adsorption kinetics models is critical Furthermore, to know the close association between the adsorption process in the dark and during light irradiation, comparing their adsorption isotherm constant is also necessary

Journal ArticleDOI
TL;DR: In this paper, the quality of groundwater for domestic and irrigation purposes in the hard rock region in Natham Taluk, Dindigul district, Tamil Nadu, India has been investigated.
Abstract: Groundwater is a major source for domestic and agricultural uses in Natham Taluk, Dindigul district, Tamil Nadu, India. The intention of this study is to determine the quality of groundwater for domestic and irrigation purposes in the hard rock region. Totally, 37 samples were collected and analysed for physical parameters that are pH, EC, TDS, TH, major cations and anions. Piper diagram shows that Ca-HCO3 and mixed Ca-Mg-Cl is the most prominent type of water. Gibbs diagram reveals that the higher concentrations of magnesium, sodium and potassium ions are accredited to geological sources such as rock-water interaction, ion exchange process and evaporation that are the major factors affecting the nature of groundwater. In view of irrigation indices, most of the sample locations are fit for irrigation use except magnesium hazard value. Additional statistical analysis, such as correlation and principal component analysis, was calculated using SPSS software. All results are indicated; weathering, rock-water interactions and anthropogenic activities are a significant factor that alters the existence of groundwater in the research area.

Journal ArticleDOI
TL;DR: The present datasets reveal that to assess the suitability of groundwater quality for drinking and irrigation uses in both Pre and Post Monsoon Season in Sarabanga River region, Tamilnadu, India based on various water quality indices, almost all sample locations are suitable for irrigation purposes.

Journal ArticleDOI
TL;DR: In this article, the improvement of air quality and human mortality rates in countries worldwide during the COVID-19 pandemic lockdown was studied using the open-source database system along with the continuous air quality monitoring station results from global data sets.
Abstract: This research was carried out using the open-source database system along with the continuous air quality monitoring station results from global data sets during the COVID-19 pandemic lockdown in India and the global. Our purpose of this research is to study the improvement of air quality and human mortality rates in countries worldwide during the COVID-19 pandemic lockdown. Worldwide air quality data were collected from > 12,000 continuous air quality monitoring stations on six continents covering 1000 major cities from over 100 countries. Here, we discussed the implementation of the open-source data set of basic air pollutants such as PM 2.5, NO2, temperature, relative humidity, and Air Quality Index variation during the pre-lockdown and lockdown pandemic COVID-19 in India and described the global aspect. An average concentration of PM 2.5 (145.51 μg/m3), NO2 (21.64 μg/m3), and AQI index (55.58) continuously decreased. The variation of PM 2.5, NO2, normally shows more than 25 μg/m3 every year, but during the COVID-19 lockdown period (April 2020) continuously decreased below 20 μg/m3. Similarly, the AQI index and meteorological factors such as temperature, relative humidity, and wind speed variation decreased significantly in the many countries in the world. In Asian countries, air quality improved during the national lockdown especially in the most polluted cities globally such as Beijing, Delhi, and Nanjing and also in developed cities like Madrid, New York, Paris, Seoul, Sydney, Tokyo. Furthermore, the reduction of particulate matter was in about 46%, and other gaseous pollutants during the lockdown period were observed in a 54% reduction. We are witnessing pollution reductions which add significantly to improvements in air quality. This is due to the massive decrease in the use of fossil fuel, which in turn reduces production and traffic in general. People nowadays are now willing to see a comparatively healthier world with bleached skies and natural ecosystems. This research finding demonstrates potential safety benefits associated with improving air quality and mortality rates during the COVID-19 pandemic, resulting in decreases in mortality rates in India and around the world.

Journal ArticleDOI
TL;DR: The findings of this study shows that comprehensive impacts of prevention, intensive medical care and surface disinfection strategies outperform in reducing the disease epidemic with optimum implementation cost.
Abstract: In this paper, we apply optimal control theory to a novel coronavirus (COVID-19) transmission model given by a system of non-linear ordinary differential equations. Optimal control strategies are obtained by minimizing the number of exposed and infected population considering the cost of implementation. The existence of optimal controls and characterization is established using Pontryagin's Maximum Principle. An expression for the basic reproduction number is derived in terms of control variables. Then the sensitivity of basic reproduction number with respect to model parameters is also analysed. Numerical simulation results demonstrated good agreement with our analytical results. Finally, the findings of this study shows that comprehensive impacts of prevention, intensive medical care and surface disinfection strategies outperform in reducing the disease epidemic with optimum implementation cost.


Journal ArticleDOI
01 Mar 2020
TL;DR: In this article, the impact of municipal solid waste dumpsite on groundwater bodies at Hyderabad, India is assessed through leachate and groundwater samples collected through pre- and post-monsoon analyzed the physicochemical, microbiological, biological and heavy metals.
Abstract: The present study aimed to assess the impact of municipal solid waste dumpsite on groundwater bodies at Hyderabad, India. Leachate and groundwater samples collected through pre- and post-monsoon analyzed the physicochemical, microbiological, biological and heavy metals. The analytical data were compared with Bureau of Indian Standards (BIS) drinking water quality standards. Water quality index (WQI), heavy metal pollution indices like heavy metal evaluation index (HEI) and degree of contamination (Cd) are calculated for groundwater samples. High total dissolve solids values in leachates revealed that they were highly contaminated with organic and inorganic salts. Biological oxygen demand values indicated that dumpsite was “old and stabilized” with decreasing biodegradability from time to time. According to WQI, about 75% of the water samples identified as “Poor” category that is not suitable for neither drinking nor domestic purposes as per BIS standards. Similarly, HEI and Cd results indicated that majority of the samples are labeled with low-metal pollution status. Spatial patterns obtained through geographic information systems using inverse distance weighted interpolation technique revealed that the concentrations of various parameters are high due to increased degradation of solid wastes during rainfall, especially during the post-monsoon. The study suggested that leachates have treated prior to disposal on land, and continuous monitoring of groundwater wells is required to minimize the pollution and potential health hazards.

Journal ArticleDOI
04 Jul 2020
TL;DR: In this article, the authors highlight the use of geospatial technologies in the fight against COVID-19 in Ghana with best practices from China where the infections originated from; present the trends in Ghana and model near future trends of the virus.
Abstract: The SARS-CoV-2 infections continue unabated in Ghana and globally. The identification of country dynamics of the virus, its spread, and country-specific interventions in tackling the menace including the application of geospatial technologies. This research sought to highlight the use of geospatial technologies in the fight against COVID-19 in Ghana with best practices from China where the infections originated from; present the trends in Ghana and model near future trends of the virus. It was evident that just as other places, Ghana has employed geospatial technologies and continues to ply unchartered paths in solutions. The trend in Ghana is in line with a population concentration and tends to record higher figures in the southern parts. It is modeled that through incessant mobility patterns, infections will spread through to the middle parts and then the northern parts. The research, therefore, recommends the use of infrared scanners to augment testing practices and enhanced tracing of infected persons as well as the use of drones for the distribution of essential services.

Journal ArticleDOI
TL;DR: In this article, a facile green synthesis of reduced graphene oxide (RGO) grafted Ag/ZnO nanocomposite in the presence of L-Methionine (L-Met) for synergetic photocatalytic degradation of methylene blue (MB) and antibacterial activities was reported.
Abstract: We have reported a facile, green synthesis of reduced graphene oxide (RGO) grafted Ag/ZnO (RGO-Ag/ZnO) nanocomposite in the presence of L-Methionine (L-Met) for synergetic photocatalytic degradation of methylene blue (MB) and antibacterial activities. L-Met shows an excellent efficiency as stabilizing and reducing agents for the synthesis of both Ag NPs and RGO. The successful synthesis of pure phase L-Met-RGO-Ag/ZnO was confirmed by XRD. According to UV-DRS analysis, the doping of Ag resulted in a decrease bandgap energy of ZnO from 3.34 eV to 3.18 eV. The mixed morphologies of the nanocomposite were studied by SEM and TEM. The photocatalytic degradation efficiency of L-Met-RGO-Ag/ZnO towards MB dye was investigated at varying initial concentrations of MB dye, H2O2, and ultrasonication. The optimum degradation efficiency of the nanocomposite (50 mg) at room temperature (25 °C) was found to be 99% with an initial MB dye concentration of 10 mg/L and 120 min contact time. The fast degradation of MB dye was observed in the presence of H2O2. The ultrasonication of the catalyst vanishes the synergetic interface of the nanocomposite, as a result, poor photocatalytic performance (85%) was observed even at a long period of contact time (210 min). Moreover, RGO-Ag/ZnO nanocomposites have shown strong antibacterial activity against both Gram-positive bacteria (B. Subtilis) and Gram-negative bacteria (E. coli). In conclusion, RGO-Ag/ZnO nanocomposite shows a promising photocatalyst for the degradation of organic dyes and antibacterial activities.

Journal ArticleDOI
TL;DR: In this paper, a copper oxide (CuO) NPs were synthesized using a copper nitrate trihydrate precursor and Catha edulis leaves extract as reducing and capping agent during the synthesis.
Abstract: Development of green technology is generating interest of researchers towards ecofriendly and low-cost methods for biosynthesis of nanoparticles (NPs). In this study, copper oxide (CuO) NPs were synthesized using a copper nitrate trihydrate precursor and Catha edulis leaves extract as a reducing and capping agent during the synthesis. The biosynthesized CuO NPs were characterized using an X-ray diffractometer (XRD), scanning electron microscopy-energy-dispersive X-ray spectroscopy (SEM-EDS), transmission electron microscope (TEM), Ultraviolet visible spectroscopy (UV-Vis), and Fourier transform infrared (FTIR) spectroscopy. XRD characterization confirmed that the biosynthesized CuO NPs possessed a good crystalline nature which perfectly matched the monoclinic structure of bulk CuO. Furthermore, the results obtained from SEM and TEM showed that the biosynthesized CuO NPs were spherical in shape. EDS characterization of the biosynthesized NPs also indicated that the reaction product was composed of highly pure CuO NPs. Moreover, the antimicrobial activities of different concentrations of CuO NPs synthesized using Catha edulis extract were also tested. Accordingly, the result showed that the highest zone of inhibitions measured were for CuO NPs synthesized using 1 : 2 ratios at 40 mg/ml solution concentration and observed to be 22 ± 0.01 mm, 24 ± 0.02 mm, 32 ± 0.02 mm, and 29 ± 0.03 mm for S. aureus, S. pyogenes, E. coli, and K. pneumonia, respectively.

Journal ArticleDOI
TL;DR: In this article, the authors synthesize nanoparticles from titanium tetrabutoxide and extract of root of Kniphofia foliosa with a ratio of 1.8862, 62.7, 70.2, and 75.2.
Abstract: Biogenic methods of synthesis of nanoparticles (NPs) using plant extracts have been given a great attention due to its nontoxicity and environmental friendliness. In this study, TiO2 NPs were synthesized from titanium tetrabutoxide and extract of root of Kniphofia foliosa. NPs of TiO2 were biosynthesized at different volume compositions of titanium tetrabutoxide to the plant extract with a ratio of 1 : 2, 1 : 1, and 2 : 1, respectively. These green synthesized NPs of TiO2 were characterized by thermogravimetric analysis (TGA/DTA), X-ray diffraction (XRD), scanning electron microscope-energy dispersive X-ray spectroscopy (SEM-EDS), transmission electron microscopy (TEM), ultraviolet-visible spectroscopy (UV-Vis), and Fourier transform infrared (FTIR) spectroscopy. TGA/DTA analysis has confirmed that the synthesized NPs of TiO2 were stable above the temperature of 500°C. The sharp and intense peaks at 2θ values of 25.3, 38.0, 47.9, 53.2, 54.8862, 62.7, 70.2, and 75.0 have confirmed formation of crystalline NPs of TiO2 in the sample of 1 : 1 and 2 : 1 ratios, and less crystalline samples for TiO2 NPs prepared in a 1 : 2 ratio. Comparison between FT-IR absorption bands of the plant extract and that of calcined NPs of TiO2 confirmed the purity of synthesized nanomaterials, except unavoidable adsorption of moisture on the surface of TiO2 NPs in an open air. The antibacterial activity of biosynthesized TiO2 NPs and that of ethanolic root extract of Kniphofia foliosa was investigated via the disc diffusion method against human pathogen bacteria strains of Staphylococcus aureus, Escherichia coli, Klebsiella pneumonia, and Streptococcus pyogenes. Among the different ratios, TiO2 (1 : 1) NP shows better performance towards Gram-negative bacteria due to its smaller average crystalline size and uniform morphology observed in SEM image relative to the other two ratios of TiO2 NPs. Antibacterial activity of the ethanolic root extract of Kniphofia foliosa itself showed better performance towards Gram-negative bacteria than NPs of TiO2 that might be due to antibacterial activity of residue of ethanol left with the plant extract.

Journal ArticleDOI
TL;DR: The NCDs were employed as a fluorescent probe for the simultaneous determination of Fe(III) and Cu(II) with a linear response in the 3–60 μM concentration range and a 0.31 μM detection limit (LOD).
Abstract: Simultaneous fluorometric determination of iron(III) and copper(II) without the use of any masking agent or additional treatment is achieved by using N-doped carbon dots (NCDs). The NCDs were hydrothermally prepared, have strongest excitation/emission peaks at 320/406 nm and a 47% quantum yield. Excitation-tunable emission is found to depend on solution pH values. This supports the involvement of surface states in the origin of the excitation dependent nature. The NCDs were employed as a fluorescent probe for the simultaneous determination of Fe(III) with a linear response in the 3–60 μM concentration range and a 0.31 μM detection limit (LOD). The probe also responds linearly to Cu(II) in the 0.5–15 μM concentration range and with a 56 nM LOD. With the addition of Cu(II), the absorption spectra of NCDs presented a clear decrease in the intensity at 312 nm followed by an increase at 360 nm. This is not observed in the presence of Fe(III). The fluorescence lifetime of NCDs (5.8 ns) is reduced by Fe(III) but not by Cu(II). Thus, the two metal ions can be simultaneously detected without the need for any reagents. The probe was employed to quantify Fe(III) and Cu(II) in spiked water, serum, and urine samples.

Journal ArticleDOI
02 Jan 2020
TL;DR: In this paper, spatial variation of physicochemical parameters were analyzed for Northeast Adama Town and the results indicated that except ASTU well 2, all samples are below the desirable limits of WHO.
Abstract: Assessment of groundwater quality is vital for the sustainable use of the resources for domestic and agricultural purposes. In this study spatial variation of physicochemical parameters were analyzed for Northeast Adama Town. Water Quality Index (WQI) and irrigation indices were used to determine the suitability of groundwater for drinking and irrigation purposes, respectively. Further, the physical-chemical results were compared with the Ethiopian standards and the World Health Organization (WHO) standards for drinking and public health. Using GIS interpolation methods in Arc GIS 10.3.1, spatial distribution maps of pH, TDS, EC, Cl, HCO3 , SO4 , Ca, Mg, Na and K, RSC, SAR, Na% were prepared. Results indicated that except ASTU well 2, all samples are below the desirable limits of WHO. The WQI results indicated that 85% of samples and 15% of samples were in good and poor categories, respectively. Irrigation indices show that the most groundwater samples have excellent water classes, indicating that they are suitable for irrigation purposes. © 2019 GATHA COGNITION All rights reserved. Article history Received: 11 November 2019 Revised: 25 December 2019 Accepted: 27 December 2019

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TL;DR: In this article, a flexible polymer nanocomposites for food packaging to inactivate microorganisms associated with foods is the demand of the present-day food industry to assure quality throughout the packaging operation.
Abstract: Abstract The application of flexible polymer nanocomposites for food packaging to inactivate microorganisms associated with foods is the demand of the present-day food industry to assure quality throughout the packaging operation. The utilization of polyvinyl alcohol (PVA) assisted zinc oxide nanocomposite for food stuff packaging has been very attractive in the recent past. Nanostructured ZnO was synthesized at optimized pH (10.5) from different ratios of zinc acetate and Moringa oleifeira leaf extract (1:7, 1:3, 1:1 and 3:1). ZnO coated polyvinyl alcohol (ZnO/PVA) nanocomposites were prepared from 5, 9, 13 and 16% by wt of ZnO and PVA using solution casting method. The thermal stability of ZnO synthesized with 1:1 ratio at pH 10.5 was investigated with TGA/DTA. The analytical techniques such as X-ray diffraction (XRD), ultra-violate visible analysis (UV-Vis), Fourier-transform infrared spectroscopy (FTIR), and scanning electron microscope (SEM) were used for the characterization of the synthesized ZnO and ZnO/PVA nanocomposites (NCs). The antibacterial activity of the synthesized ZnO and ZnO/PVA NCs were evaluated against gram negative E. coli and gram positive S. aureus bacteria. The electrochemical stability of ZnO/PVA NCs was also investigated by cyclic voltammetric (CV) method. The thermogram of ZnO indicated that the oxide was found to be stable even beyond 500°C. The SEM analysis revealed rod shaped morphology for synthesized ZnO from 1:1 ratio at pH 10.5. But the nanocomposite prepared with 5% of ZnO of (1:1) at the same pH exhibited uniformly dispersed rod-shaped particle on the surface as well as in matrix of polyvinyl alcohol film. According to XRD result, ZnO synthesized with more percentage of plant extract resulted in the small size crystallites while that with low percentage of plant extract resulted in the larger crystallite size. The antibacterial inhibition efficiency of ZnO/PVA NCs was better and found to increase with increase in the amount of ZnO.

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TL;DR: A hydrochemical study on the coastal aquifers was initiated to determine the factors affecting the groundwater chemistry in South India as discussed by the authors, where 48 groundwater samples from bore wells were collected during post monsoon period.
Abstract: A hydrochemical study on the coastal aquifers were collected initiated to determine the factors affecting the groundwater chemistry in South India. 48 groundwater samples from bore wells during post monsoon period. The samples were measured for in situ parameters and major ions following the standard procedures. The analyzed results were further interpreted using geochemical plots, ionic ratios, water quality indices, geochemical modeling and statistics. pH values in the groundwater ranged from 6.6 to 8.0 and alkaline in nature. The average value of EC was 7155 μS/cm and higher values were mostly distributed along the coastal region of the study area. From the Piper plot, hydrochemical evolution path was identified, from Ca−HCO3 (recharge waters) to mixed Ca-Mg-Cl (reverse ion exchange waters) through Ca-Cl types (leachate waters), indicating the reverse ion exchange and seawater intrusion. Saturation index reflected that Calcite was oversaturated due to availability of Ca and HCO3 ions. Factor analysis further improved the understanding of the major controlling hydrochemical processes for groundwater chemistry. The hydrochemistry of the coastal aquifer was affected by several factors such as dissolution, water-rock interaction, reverse ion exchange, seawater intrusion, and influence of minor agricultural. The water quality assessment showed that the concentration of most of the parameters exceeded the standards limit, and considered as unsuitable for drinking purposes. But they are inferred to be suitable for agricultural purposes according to SAR, Na%, RSC and PI.

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TL;DR: In this paper, a high active CuBiOS bimetal oxysulfide catalysts were successfully prepared via a feasible method, which achieved the reduction of toxic organic of 4-NP, organic dyes (MO, MB, RhB, and chromium (Cr(VI)) in the presence of NaBH4 under dark condition.

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01 Feb 2020-Heliyon
TL;DR: Investigation of households' preference for renewable source of electricity service connections and estimated potential willingness to pay for the services by considering solar PV electricity in addition to the grid-line reveals Monthly instalment-based payment is more convenient for the rural household than lump sum connection cost payment regarding the payment scheme.