1,720,963 research outputs found
Functionalized, biocompatible, and impermeable nanoscale coatings for PEEK
No full textBiologically compatible coatings that provide hermetic seal could resolve a major technological hurdle in the attempt to replace metals with polymers for biochips and active medical implants. The use of amorphous carbon/diamond like carbon (a-C:H) coatings to hermetically seal and biologically enhance polyether-ether-ketone (PEEK) for biomedical device integration in the human body was investigated. The PEEK coating functionality (sp3/sp2 ratio), hardness and thickness (70–200 nm) were controlled, by varying H2 and N2 concentration during the plasma operationwith CH4. a-C:H coatings having the highest indentation modulus of 13.5 GPa, originate out of a CH4 (90%) rich composition. Even in a mixture of 70/30H2/CH4 the hardness is 4.76 GPa, corresponding to hard and dense coatings. In all tested conditions of deposition coatings hardens was sufficient for the purpose of PEEK implants modification. The synthesized (a-C:H) nanoscale coatingswere notwater permeable as measured by the hydrolysis test, resolving the traditional challenge of swelling in wet environment. The hardness of the
coatings showed strong correlations with the thickness, surprisingly however, with no correlations with the sp3/sp2 ratio. Selected non water permeable nanoscale coating on PEEK showed strong bioactivity by being viable for human osteoblast (hFOB) and human fibroblast (hGF) cells without toxicity issues. No correlationwas observed between the coatings sp3/sp2 ratio and biological performanc
Surface modification and characterization of GO/polymer thin coatings as excellent bio-active platforms for tissue regeneration
No full textOsteo-integration and tissue regeneration are vital for the longevity, durability, and unremitting
functionality of medical implants/scaffolds implanted in vivo. It’s essential for biomaterials used for in
vivo implantation to induce the cellular secretion of growth factors, necessary for the desired tissue
generation, since the administration of artificial growth factors, in vivo, is largely prohibited. Plasma
functionalized (N2 and O2) and stabilized Graphene Oxide (GO) thin layers in a hybrid with amorphous
carbon (aC) induced the expression of vascular endothelial growth factor (VEGF) and osteoprotegerin
(OPG) growth factors in fibroblasts (hGF) and, more remarkably, in osteoblasts (hFOB) cells
confirming the suitability for tissue regeneration and osteo-integration applications. We also observed
a negative trend between hGF fibroblasts, but not hFOB osteoblasts, cellular viability and GO presence
in the hybrid films that might indicate the phenomenon of oxidative stress. We traced that back to the
presence of higher concentrations of carboxyl and the carbonyl groups on the surface of the GO rich
coatings. The above described properties provided by GO coatings might be desirable for bioselectivity
applications and for the reduction of the undesired fibrosis process that is associated with
medical implants in vivo environment. Moreover, novel plasma functionalized GO/polymer hybrid thin
coating hybrid compositions are promising candidates for tissue engineering and bioengineering
applications as excellent antimicrobial and anticancer platforms
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
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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