1,720,981 research outputs found
Analysis of Copper, Zinc and Lead using Atomic Absorption Spectrophotometer in ground water of Jimma town of Southwestern Ethiopia
No full textAims: This study was design to determine the level of heavy metal contamination of ground water in Jimma town of Southwestern Ethiopia. Methods: The sample had been collected from (6) different sites about (10) well and borehole water. Samples were analyzed using Atomic Absorption Spectrophotometer (AAS). Three heavy metals had been studied were Copper, Zinc and Lead. Their concentration and maximum contaminant levels (MCL) were compared with World Health Organization (WHO) data. The maximum contaminant levels according to WHO, for Copper, Zinc and Lead are 0.5, 3.0 and 0.01 mg/L respectively. Conclusion: From the results obtained, none of the samples analyzed for Copper (0.025 mg/L) and Zinc (0.15 mg/L) concentration was found above the MCL but for Lead (0.02202 mg/L) concentration found above the MCL. However, the metals were present in 82.86% and 91.23% of the samples analyzed respectively. Almost 86.01% of the sample had detectable level of Lead. All the Lead concentration was above the MCL. In general, 86.70% of all samples analyzed contained one or more of three heavy metals. The results obtained from this study suggest significant risk to this population given for toxicity of these metals, well and borehole water are the only source of their water supply in this environment. Copyright ª 2013, JPR Solutions; Published by Reed Elsevier India Pvt. Ltd. All rights reserve
Electrochemical Determination of Hydroquinone By Using Poly Malachite Green Modified Carbon Paste Electrode Prepared From Activated Carbon From Aframomum Cororima Husk and Graphite Powder
Full text linkHydroquinone (HQ) is the oxidation product of some aromatic compounds. HQ is widely
found in cigarette smoke, diesel engine lubricant and the chemical industry. Industrial
development has caused a huge increase in the release of potentially toxic compounds into the
atmosphere, water bodies and soils. Therefore, a simple, cheap and sensitive determination
method of HQ is highly desired. In this work, the electrochemical determination of HQ was
reported. The oxidation current response of HQ at the poly malachite green modified carbon
paste electrode (PMG-CPE) was investigated using cyclic voltammetry (CV) and linear sweep
voltammetry (LSV) methods. The performance between unmodified carbon paste electrode
(UCPE) and PMG-CPE was made toward the determination of HQ. Due to the different
interactions of the HQ at the electrode surface, the PMG-CPE electrode signal intensity of the
developed method gives much higher than UCPE in phosphate buffer solution (PBS). Under
the optimized experimental conditions, the electrode oxidation peak current was a direct
relationship with the concentration of HQ in the range of 1 μM to 75 μM and a limit of
detection (LOD) of 0.82 μM (3σ/m). The reported PMG-CPE was further applied for the
determination of HQ in waste water with acceptable recoveries
Electrochemical Determination of Dopamine at Glassy Carbon Electrode Modified With Rhodamine B
No full textIn this study, rhodamine B was synthesized and used to modify glassy carbon electrode
for the electrochemical determination of DA. Cyclic voltammetry was used to further analyze the
electrochemical properties of bare glassy carbon electrode and Rhodamine B modified glassy
carbon electrode. It was found that rhodamine B modified glassy carbon electrode exhibited
superior electro catalytic oxidation, enhanced anodic peak current, and less over potential
towards DA as compared to bare glassy carbon electrode and Experimental parameters such as,
scan rate, effect of pH, polymerization of rhodamine B were optimized. The suggested electrode
showed excellent repeatability, reproducibility, and a low detection limit. DA in a urine sample
was successfully determined using the rhodamine B modified glassy carbon electrode. Under the
optimum experimental conditions, the oxidation peak currents had good linear relationship with
DA concentrations in the range of 0.02 - 0.20 μM. In addition, the obtained sensor showed good
sensitivity, favorable repeatability, and long term stability. Finally, the proposed electrochemical
method has been successfully applied for the determination of dopamine in real samples with
satisfactory results
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe 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
Full text link“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
Full text linkWe 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
Full text linkWe 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
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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