1,721,086 research outputs found
Flame-Retardant Paper from Wood Fibers Functionalized via Layer-by-Layer Assembly
No full textThe
highly flammable character of cellulose-rich fibers from wood
limits their use in some advanced materials. To suppress the flammability
and introduce flame-retardant properties to individual pulp fibers,
we deposited nanometer thin films consisting of cationic chitosan
(CH) and anionic poly(vinylphosphonic acid) (PVPA) on fibers using
the layer-by-layer (LbL) technique. The buildup of the multilayer
film was investigated in the presence and absence of salt (NaCl) using
model cellulose surfaces and a quartz crystal microbalance technique.
Fibers were then treated with the same strategy, and the treated fibers
were used to prepare paper sheets. A horizontal flame test (HFT) and
cone calorimetry were conducted to evaluate the combustion behavior
of paper sheets as a function of the number of bilayers deposited
on fibers. In HFT, paper made of fibers coated with 20 CH/PVPA bilayers
(BL), self-extinguished the flame, while uncoated fibers were completely
consumed. Scanning electron microscopy of charred paper after HFT
revealed that a thin shell of the charred polymeric multilayer remained
after the cellulose fibers had been completely oxidized. Cone calorimetry
demonstrated that the phosphorus-containing thin films (20 BL is ∼25
nm) reduced the peak heat release rate by 49%. This study identifies
a unique and highly effective way to impart flame-retardant characteristic
to pulp fibers and the papers made from these fibers
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
Multilayer nanocoatings capable of separating gases, killing bacteria and stopping fire
Get PDFLayer-by-layer (LbL) assembly is a conformal coating “platform” technology capable of imparting a multiplicity of functionalities on nearly any type of surface in a relatively environmentally friendly way. At its core, LbL is a solution deposition technique in which layers of cationic and anionic materials (e.g. nanoparticles, polymers and even biological molecules) are built up via electrostatic attractions in an alternating fashion, while controlling process variables such as pH, coating time, and concentration. Here we are producing nanocomposite multilayers (50 – 1000 nm thick), having 10 – 96 wt% clay, that are completely transparent and exhibit oxygen transmission rates below 0.005 cm3/m2•day. This exceptional oxygen barrier makes these coatings interesting for food, consumer products and flexible electronics packaging. These same ‘nanobrick wall’ assemblies are very conformal and able to impart flame resistance to highly flammable foam and fabric by uniformly coating the complex three-dimensional geometries. I’ll also describe how all-polymer thin films can separate H2 from N2 (or CO2) with selectivity greater than 2000, which exceeds other commonly used gas separation membranes (including zeolites). These films can also be produced with graphene oxide to generate high barrier and low sheet resistance. If there’s time, our work on antimicrobial and UV-resistant films will also be described. All of these nanocoatings are water-based and processing occurs under ambient conditions in most cases. Furthermore, these nanocoatings can be deposited in a commercially-feasible manner. Our work in these areas has been highlighted in C&EN, ScienceNews, Nature, Smithsonian Magazine, Chemistry World and various scientific news outlets worldwide. For more information, please visit my website: http://nanocomposites.tamu.ed
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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