1,720,972 research outputs found
Trichloramine reactions with nitrogenous and carbonaceous compounds: Kinetics, products and chloroform formation
No full textTrichloramine is a hazardous disinfection by-product that is of particular relevance in indoor swimming pools. To better understand its fate in pool waters, apparent second order rate constants (kapp) at pH 7 for its reaction with several model compounds were determined. kapp values at pH 7 for nitrogenous compounds were found to increase in the following order: ammonia ∼ amides (∼10-2-10-1 M-1 s-1) < primary amines (∼10-1-100 M-1 s-1) < relevant body fluid compounds (l-histidine, creatinine) (∼100-101 M-1 s-1) < secondary amines (∼101-102 M-1 s-1) < trimethylamine (∼103 M-1 s-1). kapp values at pH 7 of trichloramine with hydroxylated aromatic compounds (∼102-105 M-1 s-1) are higher than for the nitrogenous compounds and depend on the number and position of the hydroxyl groups (phenol < hydroquinone < catechol < resorcinol). The measurement of kapp as a function of pH revealed that mainly the deprotonated species react with trichloramine. The reaction of trichloramine with Suwannee River and Pony Lake fulvic acid standards showed a decrease of their reactivity upon chlorination, which can be related to the electron donating capacity and the SUVA254. Chlorinated nitrogenous compounds (e.g. uric acid) also have a reduced reactivity with trichloramine. Hence, the residual chlorine in pool water hinders a fast consumption of trichloramine. This explains why trichloramine degradation in pool water is lower than expected from the reactivity with the estimated bather input. Trichloramine also has the potential to form secondary disinfection by-products such as chlorinated aromatic compounds or chloroform by electron transfer or Cl+-transfer reactions. The chloroform formation from the reaction of trichloramine with resorcinol occurs with a similar yield and rate as for chlorination of resorcinol. Since the trichloramine concentration in pool water is commonly about one order of magnitude lower than the free chlorine concentration, its contribution to the disinfection by-product formation is assumed to be minor in most cases but might be relevant for few precursors (e.g. phenols) that react faster with trichloramine than with free chlorine.LTQ
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
Trichloramine in swimming pool water: Analysis methods, factors influencing its fate and effects of UV treatment
No full textkoamabayili/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
Biophysical characterization of protein-protein interactions with mass photometry: In-vitro characterization of protein interactions with mass photometry
Get PDFInteractions between biomolecules control the processes of life in health and their malfunction in disease, making their characterization and quantification essential. We first explore the capabilities of established methods for binding affinity measurements of protein-protein interactions and present mass
photometry in this context. We explain that immobilization- and label-free analytical techniques are desirable because of their simplicity and minimal invasiveness, but that they struggle with quantifying tight interactions and resolving co-existing species.
After a bench-marking process we show that mass photometry can accurately count different unlabelled biomolecules at the single-molecule level, distinguishing them by molecular mass, thereby revealing the relative abundances of different oligomeric states and stoichiometries of complexes in vitro. We develop and characterize a single-shot measurement method to determine binding affinities over four orders of magnitude at equilibrium for both simple and complex stoichiometries, as well as the associated kinetics in experiments with minimal sample consumption (fmol) and efficient experimental procedures
(< few minutes per sample).
We then present applications of this method for protein-protein interactions quantification of biotherapeutics and glycoproteins in the field of cancer, autoimmune disease, HIV and SARS-CoV-2 research.
These results introduce mass photometry as a rapid, simple and label-free method for studying sub-micro molar binding affinities, with potential to become a universal approach for characterizing wide range of biomolecular interactions
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