1,721,069 research outputs found
An investigation of Poly (caprolactone-co-glycolide) interaction with bioactive proteins and cellular responses
No full textThe objective of the present investigation is to systematically evaluate the role of polymer crystallinity on osteoblast adhesion, proliferation, osteogenic gene expression and bioactive protein adsorption using a series of poly(caprolactone-co-glycolide) (PCL-PGA) polymers. Five compositions of pure PCL and PGA, and PCL-PGA intermediate copolymeric compositions in ratios of 25:75, 35:65 and 45:55, were selected. These polymers were fabricated into thin films by compression molding. The samples were characterized using scanning electro microscopy (SEM) for surface morphology, differential scanning caloriometry (DSC) for crystallinity, contact angle measurement for hydrophobicity (CA), and atomic force microscopy (AFM) for nanotopography. The PCL-PGA films demonstrated similar morphology, hydrophobicity and nanotopography whereas they differed significantly in crystallinity. Cell adhesion and proliferation, as well as osteogenic gene expression were evaluated with osteoblasts (HEPM 1486) on PCL-PGA surfaces. Recombinant human growth and differentiation factor 5 (rhGDF-5) and Fibronectin (Fn) were adsorbed from single protein solutions using depletion method and quantified using bicinchoninic acid (BCA) protein and radiolabelling assay. The protein-adsorbed surface nanotopography was analyzed using AFM. In the cellular responses experiments, amorphous/flexible PCL-PGA 35:65 supports osteoblast growth and promotes osteogenic gene expression significantly better than the crystalline PCL and PGA. These studies demonstrated that crystallinity and rigidity played major roles in determining cell responses with PCL-PGA polymers. Protein adsorption study results indicate that rhGDF-5 adsorbed to a higher extent on PCL surfaces and least on PGA surfaces. Reduced rhGDF-5 (a more hydrophilic and flexible protein form adsorbed significantly in greater amounts on all PCL-PGA substrates, demonstrating that the conformation and hydrophibicity of rhGDF-5 played a major role in its adsorption to PCL-PGA surfaces. Fn, a 450 kDa protein, contains multiple binding motifs with varied hydrophobicity. Binding motifs of Fn fragments strongly impacted their adsorption to PCL-PGA surfaces. The adsorption of Fn 70 kDa fragment on PCL-PGA polymers was found to favor binding to PCL material with the greatest adsorption on pure PCL surfaces, similar to the full length of Fn molecule. Collectively, these studies demonstrate that Fn (70 kda) played a major role in full-length Fn adsorption to PCL-PGA substrates.Ph.D.Includes abstractVitaIncludes bibliographical referencesby Han Cu
Investigation of a novel elastic-mechanical wheel transmission under light duty conditions
Full text linkA novel 'Elastic Engagement and Friction Coupled' (EEFC) mechanical transmission has been proposed recently in which the power is transmitted through elastic tines on the surfaces of the driving and driven wheels. This study introduces new variations of EEFC mechanical wheel transmission ( broadly emulating a gear-pair) with small contact areas for use under light duty conditions. Because a drive of this type inevitably has a strong statistical component, theoretical analysis of the geometrical and mechanical relationships has been attempted by using linear modeling and empirical weightings. Several simple forms of the EEFC wheel transmission are tested under limiting ( slip) conditions for transmission force and transmission coefficients against normal load. Normalized standard deviation of these parameters is used to summarize noise performance. Models and experiments are in reasonable agreement, suggesting that the model parameters reflect important design considerations. EEFC transmissions appear well suited to force regimes of a few tenths of a newton and to have potential for use in, for example, millimetre-scale robots
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
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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