1,720,962 research outputs found
EXTRACTION AND EVALUATION OF OIL FROM GREEN ALGAE CLADOPHORA GLOMERATA BY HEXANE/ETHER MIXTURE
Get PDFThe overall aim of this study was to grow green algae Cladophora glomerata, extract oil from it, and characterize the extracted oil to gain insight into its physicochemical properties. The effects of parameters affecting the solvent extraction process, temperature, time and biomass particle size were investigated at a fixed solvent ratio of 4:1 hexane to ether. An optimization of oil separation from algae biomass via the solvent extraction method was studied. The obtained results showed that at the extraction temperature of 60 oC, extraction time of 2.5 h, and the particle size of ≤0.6 mm, the maximum oil yield was 18.3% from the process. The functional group analysis revealed the presence of alkane, esters, carboxylic acid, and unsaturated groups on the extracted oil, while the result from the fatty acid profile analysis confirmed the dominance of oleic acid. The physicochemical properties of the extracted algal oil conformed to the ASTM standard
Review on Prevalence of Waterborne Diseases in Nigeria
Get PDFThe problems associated with drinking water encountered in some parts of Nigeria have created a public Health concern. Governments that are unserious about provision of safe drinking water are liable to experience outbreak of waterborne diseases. Nigeria is one of the countries suffering from the crippling burden of water related diseases. The common diseases of drinking water in Nigeria include Cholera, Dracunculiasis, Hepatitis, Typhoid and Filariasis. In this research study, the profile of water related diseases in Nigeria from 2002-2008 was considered. This work was carried out with a view to assessing the successes recorded and problem encountered by governments: analyze the trend and spartial dimension of these diseases in Nigeria and to
suggest necessary recommendations for proper management. Data were got from National Bureau of Statistics, Abuja (NBS). Microsoft excel was employed in analyzing the data. From the result obtained, it was revealed that typhoid ranked the highest, followed by cholera, hepatitis and dracucunliasis. Based on the problems facing Nigeria, it is strongly recommended that ministries of water resources and environment at both state and federal levels take the following steps: organize sensitization programmes addressing waterborne diseases, work closely with world health organization (WHO) and other health bodies to provide direct
necessary support to Nigerian government and mitigate unsafe drinking water and waterborne diseases in Nigeria
Equilibrium, Kinetic and Thermodynamic Studies of theAdsorption of Heavy Metals from Aqueous Solution by ThermallyTreated Quail Eggshell
Get PDFBackground and Objective: Nowadays, the contamination of water resources by heavy metals has resulted in serious health issues. Themetals in their elemental as well as chemically combined form are toxic, non-degradable and persistence in nature. Thus, there is needto develop a simple, efficient and economical method for removing dissolved heavy metals from water/wastewater. In the presentstudy, it was aimed to prepare a new adsorbent from agricultural waste in order to remove Cu2+ and Zn2+ from aqueous solution.Materials and Methods: Calcium oxide (CaO) based material was prepared from quail eggshell, characterized and used as adsorbent forthe removal of Cu2+ and Zn2+ from aqueous solution. Calcined quail eggshell at 900EC was studied and exhibited high adsorption capacity.The effects of variables affecting the adsorption process, contact time, adsorbent dosage, temperature and initial heavy metalsconcentration were investigated at fixed pH of 4.5. Results: At contact time of 30 min, adsorbent dosage of 1.5 g, temperature of 35ECand initial Cu2+ and Zn2+ concentration of 150 mg LG1, the maximum heavy metals uptake could be achieved. Based on the value ofcorrelation coefficient, the experimental results for Cu2+ best fitted the Langmuir isotherm model with monolayer adsorption capacityof 13.49 mg gG1, while Freundlich isotherm model was best fitted to the experimental results for the Zn2+ adsorption. The kinetics andthermodynamic behaviours of the adsorption process were also investigated. Conclusion: The obtained results showed that theexperimental data were in good agreement with pseudo-second-order kinetic model. The results from thermodynamic analysis revealedthat the process is spontaneous and endothermi
ADSORPTION OF CATIONIC DYE FROM AQUEOUS SOLUTION USING COMPOSITE CHICKEN EGGSHELL - ANTHILL CLAY: OPTIMIZATION OF ADSORBENT PREPARATION CONDITIONS
Get PDFA composite adsorbent was prepared from anthill and eggshell mixture, using an incipient wetness impregnation method and it was used for an adsorption of cationic dye (methylene blue, MB) from an aqueous solution. The effects of three preparation parameters including calcination temperature, calcination time and mixing ratio of eggshell to anthill on the MB uptake were investigated using the central composite design (CCD) of response surface methodology (RSM). A quadratic model was developed to predict the response with a high accuracy. The optimal adsorbent sample was characterized by scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy and X-ray fluorescence (XRF) spectroscopy. The obtained results revealed that the calcination temperature significantly affected the MB adsorption. The optimum MB uptake of 23.87 mg/g was achieved under the optimum conditions including a calcination temperature of 823.45 °C, calcination time of 3.54 h and eggshell/anthill mixing ratio of 1.89:1. A detailed characterization of an optimal adsorbent sample confirmed the presence of pores, active functional groups and various molecular adsorption sites on its surface. Equilibrium adsorption isotherms and kinetics were also studied and it was revealed that the isotherms and kinetics data fitted well to the Freundlich model and pseudo-second-order kinetics model, respectively
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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