1,721,180 research outputs found
Kinetics and Equilibrium Studies for Removal of Reactive Red 198 From Aqueous Solutions Using Zero Valent Iron powder
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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
Comparison of Sonolysis, Photolysis, and Photosonolysis for the Degradation of Organic Matter
No full textPhenol is one of the most common compounds found in the effluents of many industries such as petroleum refining and petrochemicals, pharmaceuticals, pesticides, paint and dye industries, organic chemicals manufacturing, etc. Due to the high toxicity of phenol, the contamination of bodies of water with this chemical is a serious problem for the environment and human health. In this study, the sonochemical, photochemical, and photosonochemical degradation of phenol in an aqueous solution were investigated. The sonochemical and photochemical experiments were carried out using a bath sonicator (500 W) working at 35 and 130 kHz frequencies and a 400W medium pressure UV lamp. Experiments were performed at initial concentrations varying from 1 to 100 mg L-1. The effects of such parameters as pH, initial phenol concentration, and oxidation period have been determined. Results showed that the effects of ultrasound wave for phenol oxidation were mainly due to hydroxyl radical production during cavitation-induced water decomposition. However, low rates of sonochemical destruction of phenol in water solution obtained. In the sonochemical process, phenol underwent degradation at a faster rate at 130 kHz than 35 kHz. Besides, it was shown that reaction rates involving hydroxyl radicals (hydrogen peroxide formation and phenol oxidation) had a maximum value at higher frequencies. The best yield was observed at 130 kHz for phenol degradation perhaps due to the greater availability of hydroxyl radical on the outer surface of cavitation bubbles. It was found that the rate of photochemical degradation of phenol was higher than sonochemical destruction. Also, the results showed that the combination of ultrasound wave and ultraviolet irradiation was considerably more effective than either ultrasound or ultraviolet light alone. Thus, based on the results of this study, the synergistic action of ultrasound and ultraviolet light is confirmed. This may be the result of three different oxidative processes: direct photochemical action, high frequency sonochemistry, and reaction with ozone (produced by UV irradiation of air). The results of the study showed that the degradation of phenol was increased by decreasing both pH value and phenol concentration in all the processes used
Health risk assessment to fluoride in drinking water of rural residents living in the Poldasht city, Northwest of Iran
No full textHumic Acid Removal from Aqueous Environments by Electrocoagulation Process Using Iron Electrodes
Get PDFAt present study the performance of electrocoagulation process using iron electrodes sacrificial anode has been investigated for removal of HA from artificial aqueous solution. The experiments were performed in a bipolar batch reactor with four iron electrode connected in parallel. Several working parameters, such as initial pH (3, 5, 7, and 9), electrical conductivity (50 V) and reaction time were studied in an attempt to achieve the highest removal capacity. Solutions of HA with concentration equal 20 mg L-1 were prepared. To follow the progress of the treatment, samples of 10 ml were taken at 15, 30, 45, 60, and 75 min interval. Finally HA concentration was measured by UV absorbance at 254 nm (UV254) and TOC concentration was measured by TOC Analyser. The maximum efficiency of HA removal which was obtained in voltage of 50 V, reaction time of 75 min, initial concentration 20 mg L-1, conductivity 3000 µS/Cm and pH 5, is equal to 92.69%. But for natural water samples at the same optimum condition removal efficiency was low (68.8 %). It can be concluded that the electrocoagulation process has the potential to be utilized for cost-effective removal of HA from aqueous environments
Health Risk Assessment of Heavy Metals in Vegetables in an Endemic Esophageal Cancer Region in Iran
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