1,720,987 research outputs found
Sorption of Pb(II), Cd(II) and Ni(II) From single and multimetal solutions by recycled waste porous glass
No full textSelective sorption of lead, cadmium, and nickel ions on recycled waste porous glass beads was investigated. Single-metal equilibrations
were carried out in demineralized water and ternary metal equilibrations were carried out in demi- and tap water. Freundlich
isotherm gave a good correlation of the experimental data. Maximum metal retention (qmax) in single-ion solutions were 18.66 mg=
gRPWG (0.090 mmol=gRPWG), 4.83mg=gRPWG (0.043 mmol=gRPWG), 4.00mg=gRPWG (0.068 mmol=gRPWG), respectively, for Pbþ2,
Cdþ2, and Niþ2, and lower figures were in the case of ternary systems: 13.50 mg=gRPWG(0.065 mmol=gRPWG), 2.23 (0.020 mmol=
gRPWG), 2.05 mg=gRPWG(0.034 mmol=gRPWG), respectively, for Pbþ2, Cdþ2, and Niþ2, with further drastic reduction in tap water.
Metal exhausted beads were used as thermal insulators in cement mortars, minimizing their potential impact in the environment
Hydrodynamic and physico-chemical characterization of a porous material based on recycled porous glass as a filtration/sorption media for constructed wetlands
No full textPhotocatalytic Degradation of Azo Dyes. Pilot Plant Investigation
No full textThe UVB-induced photocatalytic degradation of Methyl Red and Methyl Orange (azo dyes used in the textile
industry) containing solutions was carried out by the use of a laboratory-scale pilot plant where the catalyst, TiO2 (anatase), was
immobilized at the bottom of a channel through which the liquid was recirculated under UVB irradiation. The plant was
preliminarily characterized hydrodynamically, i.e., flow-rate, hydraulic gradients, and residence time. Photodegradation kinetics
were followed by UV−vis absorption measurements of the residual dye concentration in the liquid-phase, and the synergistic
effects of the catalyst and radiation in promoting the abatement of dyes was demonstrated in the concentration range 0.3−5.0
mg/L. Kinetic data were correlated by the use of first-order (or pseudo-first-order) models up to the concentration range 0.7 mg/
L; at higher concentrations, zero-order models (pure catalytic control) better correlated the experimental data. Photocatalytic
degradation of Methyl Red was faster than Methyl Orange, possibly due to the Coulomb repulsion of the negatively charged
sulfonate functionalities present on this latter compound. A better hydrodynamic of the liquid recirculating in the channel, i.e.,
higher flow rate (lower contact time), associated with an improved surface catalyst renovation and a higher frequency of
exposition of the substrate to the UVB radiation, together with an improved oxygen dissolution in the liquid-phase, played a
positive role in the overall kinetic performance
Photocatalytic Oxidation of Organic Micro-Pollutants: Pilot Plant Investigation and Mechanistic Aspects of the Degradation Reaction
No full textAn innovative pilot plant based on UVB and TiO2 (Anatase) allowed for photocatalytic degradation of organic micro-pollutants. The catalyst was immobilized onto a channel through which the solution containing a target molecule (Methylene Blue, MB) was recirculated. Due to the cationic nature of the MB substrate, the adsorption reaction onto the catalyst surface provided a significant contribution to the overall degradation mechanism due to the negatively charged surface at neutral pH (TiO2 pHzpc=6.8). The influence of the initial MB concentration was investigated in the range 0.3-2.0 mgL-1 with the Langmuir–Hinshelwood model showing good data correlations at concentrations up to 0.7 mgL-1, whereas at higher concentrations a pure zero-order (catalytic) kinetic trend was observed. Flow-rate of the recirculating solution sensibly influenced kinetics after the larger volumes of liquid exposed to UVB/TiO2 and to the better oxygen saturation in the liquid-phase. UV-Vis and HPLC-MS/MS experimental determinations allowed for identification of MB residual concentration and by-products
Photocatalytic Oxidation of Organic Micro-Pollutants: Pilot Plant Investigation and Mechanistic Aspects of the Degradation Reaction
No full textAn innovative pilot plant based on UVB and TiO2 (Anatase) allowed for photocatalytic degradation of organic micro-pollutants. The catalyst was immobilized onto a channel through which the solution containing a target molecule (Methylene Blue, MB) was recirculated. Due to the cationic nature of the MB substrate, the adsorption reaction onto the catalyst surface provided a significant contribution to the overall degradation mechanism due to the negatively charged surface at neutral pH (TiO2 pHzpc=6.8). The influence of the initial MB concentration was investigated in the range 0.3-2.0 mgL-1 with the Langmuir–Hinshelwood model showing good data correlations at concentrations up to 0.7 mgL-1, whereas at higher concentrations a pure zero-order (catalytic) kinetic trend was observed. Flow-rate of the recirculating solution sensibly influenced kinetics after the larger volumes of liquid exposed to UVB/TiO2 and to the better oxygen saturation in the liquid-phase. UV-Vis and HPLC-MS/MS experimental determinations allowed for identification of MB residual concentration and by-products
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
- …
