1,721,077 research outputs found
Equine road transportation in New Zealand: human factors contributing to the risk of injury
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Sorption of CO2/CH4 Mixtures in a Polymer of Intrinsic Microporosity (PIM-1): Effect of Temperature
No full textPrior analysis of permselectivity in high free volume glassy polymers for gas separation shows that solubility selectivity is an important factor. The aim of this work is the study of solubility selectivity with respect to CO2/CH4 mixture of a polymer of intrinsic microporosity (PIM-1). Sorption experiments were carried out at 25°C, 35°C and 50°C up to a pressure of 35 atm at three molar fractions of CO2 (10.9, 31.3, 50.9%). Pressure decay equipped with gas chromatograph was used for the experiments.
The results show that solubility coefficient of CO2 is lower for mixed gas experiment than for pure gas experiment, as well as the solubility coefficient of CH4, however the decrease of solubility coefficient of CH4 is higher than that of CO2. This behaviour gives rise to mixed gas solubility selectivity values higher than corresponding pure gas solubility selectivity. Sorption enthalpies were calculated at different gas mixture compositions
Sorption of CO2/CH4 Mixtures in TZ-PIM Membrane at Different Temperatures
No full textMixed gas sorption of CO2/CH4 in TZ-PIM (PIM containing tetrazole unit) was characterized at three different temperatures 25°C, 35°C and 50°C and three molar fraction of CO2, 11.3% CO2, 30.7% CO2 and 50.3% CO2 up to a pressure of 35 atm. Pressure decay equipped with gas chromatograph was used for the experiment.
Solubility selectivity of TZ-PIM for CO2/CH4 mixture is higher than solubility selectivity of PIM-1. This is due to the tetrazole group which improves the solubility of CO2 while leaving unaffected the solubility of CH4. Solubility coefficient for both gases decreases with increasing temperature
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
Gas Permeability in a Polymer of Intrinsic Microporosity (PIM-1): Effect of Time and Heat Treatments
No full textEffect of thermal treatment on the CO2 and CH4 sorption and diffusion in PIM-1 and TZ-PIM membranes
No full textIt is well known that the sorption and transport properties of high free volume glassy polymers do vary significantly with time due to physical ageing that lowers the overall free volume and consequently gas permeability. In this work we perform a series of tests in which the ageing of polymeric membrane films based on a polymer of intrinsic microporosity (PIM-1) and TZ-PIM (PIM containing tetrazole unit) is induced with high temperature treatments under vacuum. The solubility and diffusivity values of CO2 and CH4 are measured at different pressures up to 32 atm and at 50°C within a pressure decay equipment on membranes 1) as cast; 2) thermally pre-treated at 120, 140 and 160°C. The effect of thermal treatment is more evident on the diffusivity than on the solubility coefficient, in both types of membranes. In particular the diffusivity of both gases decreases with increasing heat treatment temperature. Trends of diffusivity with concentration are also thoroughly inspected
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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