1,720,999 research outputs found
Ultrasound-Assisted Hydroxyapatite-Decorated Breath-Figure Polymer-Derived Ceramic Coatings for Ti6Al4V Substrates
No full textThe introduction of nanoparticles (NPs) into the breath-figure-templated self-assembly (BFTSA) process is an
increasingly common method to selectively decorate a surface porous structure. In the field of prosthetic devices, besides controlling
the morphology and roughness of the structure, NPs can enhance the osteointegration mechanism because of their specific ion
release. Among the most widely used NPs, there are silica and hydroxyapatite (HAp). In this work, we propose a novel one-stage
method to fabricate NP-decorated surface porous structures that are suitable for prosthetic coating applications. This technique
combines the classical direct BFTSA process with the cavitation effect induced by an ultrasonic atomizer that generates a mist of
water droplets with embedded NPs. Coatings were successfully obtained by combining a UV cross-linkable polymer precursor,
alkoxy silicone, with synthesized HAp NPs, on Ti6Al4V alloy discs. The cross-linked polymeric surface porous structures at selected
concentrations were then pyrolyzed in an ammonia atmosphere to obtain a silicon oxynitride (SiON) ceramic coating. Herein, we
report the chemical and morphological analyses of both the polymeric and ceramic coatings as well as the effect of NPs at the
interface
Bioreactor Design for Dynamic Process Optimization in Tissue Engineering
No full textTissue engineering is an interdisciplinary field in which cell biology, biomaterials science, and surgery are combined and its main goal is to repair, replace and reproduce tissues and organs.
Following this procedure, cells are seeded on proper scaffolds and induced in sequence to adhere, eventually differentiate, proliferate and finally to produce the wanted extracellular matrix (ECM). During cell culture, the usefulness of applying proper physiological-like stimuli, i.e., biochemical but also mechanical signals to drive and accelerate both cell differentiation and ECM production has been demonstrated.
Tissue regeneration can be either conducted entirely in vivo or assisted by a previous in vitro phase. Considering the latter situation, a bioreactor can be defined as any apparatus that attempts to mimic physiological conditions in order to maintain and encourage tissue regeneration in dynamic conditions. Dynamic cell cultures using bioreactors can be considered a good intermediate step between the conventional in vitro static approach and in vivo studies. Therefore it is possible to promote the formation of the specific tissue by simulating physiological conditions via the application of specific mechanical and biochemical stimuli.
The proposed work is focused on the design and development of bioreactors for bone and cartilage regeneration, in which optimal cell culture conditions are controlled (temperature, nutrients, carbon dioxide and oxygen levels), and mechanical stimuli are applied on the cell constructs. This study presents a wide investigation concerning these mechanical stimulations in order to understand the best cell culture parameters for the activations of cells, naturally accustomed to similar stresses inside the joint. In particular, direct compression, change in hydrodynamic pressure and perfusion modes are compared and analyzed
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
BioMIPs: molecularly imprinted silk fibroin nanoparticles to recognize the iron regulating hormone hepcidin
Full text link: The possibility to prepare molecularly imprinted nanoparticles from silk fibroin was recently demonstrated starting from methacrylated silk fibroin and choosing a protein as template. Here, we attempted the imprinting of fibroin-based molecularly imprinted polymers (MIPs), called bioMIPs, using as a template hepcidin that is a iron-metabolism regulator-peptide, possessing a hairpin structure. A homogeneous population (PDI < 0.2) of bioMIPs with size ~50 nm was produced. The bioMIPs were selective for the template; the estimated dissociation constant for hepcidin was KD = 3.6 ± 0.5 10-7 M and the average number of binding sites per bioMIP was equal to 2. The bioMIPs used in a competitive assay for hepcidin in serum showed a detection range of 1.01 10-7- 6.82 10-7 M and a limit of detection of 3.29 10-8 M
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
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