1,721,079 research outputs found
The influence of initiator concentration on selected properties of thermosensitive poly(Acrylamide-co-2-acrylamido-2-methyl-1-propanesulfonic acid) microparticles
Full text linkThermosensitive polymers PS1–PS5 were synthesized via the surfactant free precipitation polymerization (SFPP) using 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPSA), and potassium persulfate (KPS) at 70◦C in aqueous environment. The effect of KPS concentrations on particle size and lower critical temperature solution (LCST) was examined by dynamic light scattering (DLS). The conductivity in the course of the synthesis and during cooling were investigated. The structural studies were performed by attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), H nuclear magnetic resonance (1H NMR), thermogravimetric analysis (TGA/DTA) and powder X-ray diffraction (PXRD). ATR-FTIR,1H NMR and PXRD data confirmed the polymeric nature of the material. TGA/DTA curves demonstrated thermal stability up to approx. 160◦C. The effect of temperature on the hydrodynamic diameter (HD) and zeta potential (ZP) were evaluated by dynamic light scattering (DLS) and electrophoretic mobility (EM) in 18–45◦C range. The LCST values were between 30 and 34◦C. HD and polydispersity index (PDI) of aqueous dispersions of the synthesized polymers PS1–PS5 at 18◦C were found to be 226 ± 35 nm (PDI = 0.42 ± 0.04), 299 ± 145 nm (PDI = 0.49 ± 0.29), 389 ± 39 nm (PDI = 0.28 ± 0.07), 584 ± 75 nm (PDI = 0.44 ± 0.06), and 271 ± 50.00 nm (PDI = 0.26 ± 0.14), respectively. At 18◦C the ZPs of synthesized polymers suspensions were −13.14 ± 2.85 mV, −19.52 ± 2.86 mV, −7.73 ± 2.76 mV, −7.99 ± 1.70 mV, and −9.05 ± 2.60 mV for PS1–PS5, respectively. We found that the initiator concentration influences the physicochemical properties of products including the size of polymeric particles and the LCST
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
Electrical Conductivity as an Informative Factor of the Properties of Liposomal Systems with Naproxen Sodium for Transdermal Application
Full text linkLiposomal preparations play an important role as formulations for transdermal drug delivery; however, the electrical conductivity of these systems is sparingly evaluated. The aim of the study was to outline the range of the values of electrical conductivity values that may be recorded in the future pharmaceutical systems in the context of their viscosity. The electrical conductivity, measured by a conductivity probe of k = 1.0 cm−1, and the dynamic viscosity of liposomal and non-liposomal systems with naproxen sodium, embedded into a methylcellulose hydrophilic gel (0.25%), were compared with data from preparations without naproxen sodium in a range reflecting the naproxen sodium concentrations 0.1·10−2–9.5·10−2 mol/L. The specific conductivity covered a 1.5 μS·cm−1–5616.0 μS·cm−1 range, whereas the viscosity ranged from 0.9 to 9.4 mPa·s. The naproxen sodium highly influenced the electrical conductivity, whereas the dynamic viscosity was a moderate factor. The observed phenomena may be ascribed to the high mobility of sodium ions recruited from naproxen sodium and the relatively low concentrations of applied methylcellulose. The assembly of lecithin in liposomes may have lowered the specific conductivity of the systems with naproxen sodium. These measurements will be further developed for implementation as simple assays of the concentrations of active pharmaceutical ingredient in release experiments of preparations proposed for dermatological applications
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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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