1,720,959 research outputs found
Gel-type polyacrylic resins cross-linked with trimethylolpropanetrimethacrylate: the issue of their nanostructure unveiled with a combination of Inverse Steric Exclusion Chromatography (ISEC), ESR and CP MAS 13C NMR spectrometries
No full textAbstract: Six gel-type functional resins,
that is, three poly-DMAA-co-TMPTP
(DMAA=N,N-dimethylacrylamide,
TMPTP=trimethylolpropyltrimethacrylate)
samples with different degrees
of cross-linking (0.6, 1.2, 1.7% mol)
and three poly-DMAA-co-MA-co-
TMPTP (MA=methacrylic acid, ca.
5.5% mol) samples with 1.7, 3.5, and
7% mol cross-linking were investigated
with ISEC (inverse steric exclusion
chromatography), and ESR and CPMAS
(cross polarization magic angle
spinning) 13C NMR spectroscopy after
swelling in water and other solvents.
This unprecedented combination of
conceptually independent physicochemical
techniques provides a thorough
overall consistent picture of the
morphology of the resins on the nanometer
scale and of the molecular accessibility
of the swollen polymer framework
to the paramagnetic probe TEMPONE
(2,2,6,6-tetramethyl-4-oxo-1-
oxypiperidine) and to selected solvents
Catalytic activity of bovine lactoperoxidase supported on macroporous poly(2-hydroxyethyl methacrylate-co-glycidyl methacrylate)
No full text2-Hydroxyethyl methacrylate (HEMA) and glycidyl methacrylate (GMA) (molar ratio 85/15) are copolymerised
upon c-ray exposure at 78 C in the presence of water to give a hydrophilic resin with a porosity that favours the
anchoring of bovine-lactoperoxidase (LPO). The resin, after mincing and sieving, is obtained as irregular microparticles
with size ranging from 80 to 1000 lm. The morphology of the resin in the swollen state is investigated with Inverse
Steric Exclusion Chromatography and ESR. The catalytic activity of immobilised and soluble LPO is monitored
and compared for 14 days at 4 C as well as enzyme stability toward thermal inactivation and resistance to denaturing
agents (acidity, urea, organic solvents). The results reveal a higher stability of supported LPO both in aqueous and
organic media as compared with the free enzyme. Evaluation of kinetic parameters of immobilised LPO suggests that
the enzyme turns out to be mainly linked to the external surface of the supporting particles
Cross-linked poly-4-vinylpiridines as useful supports in metal catalysis: micro- and nanometer scale morphology
No full textGoing 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
Nanostructure and molecular accessibility of gel-type resins for supported bio-catalysis. Part I. Poly-hydroxyethylmethacrylatehydroxypropylmethacrylate-trimethylolpropanetrimethacrylate
No full textVariations 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
- …
