1,721,006 research outputs found
Advanced biomimetic implants based on nanostructured coatings synthesized by pulsed laser technologies.
No full textCalcium Phosphates (CaPs) are alternative substitutes for human bones and so primary candidates for the manufacturing of medical implants. Unfortunately, they do not withstand stress in bulk. To overcome this obstacle, a solution was developed to cover the metallic implants with functional biomimetic layers.
Pulsed laser deposition (PLD) proved to be a competitive method to grow high-quality biomaterial thin films. Nevertheless, in case of very complex delicate biomolecules (such as organic and biopolymeric materials), PLD provokes an irreversible damage of the chemical bonds and thus the compositional change in the deposited film. This disadvantage is eliminated by matrix assisted pulsed laser evaporation (MAPLE), capable to transfer large molecular mass compounds at very low temperatures.
We review in this chapter the potential of PLD applied to different types of simple and/or doped CaP coatings. We also scrutinize the extension of MAPLE to the synthesis of hybrid organic-inorganic bionanocomposites for advanced biomimetic implants. Expected development and progress of the new in-vitro and in-vivo studies are discussed
Measurements of Quantum Efficiency of Mg Films Produced by Pulsed Laser Ablation Deposition for Application to Bright Electron Sources
No full textPhotoemission Characteristics of PLD Grown Mg Films under UV Laser Irradiation
No full textIn this paper we report a detailed description of the laser cleaning procedure
and emission performance measurement on a pulsed laser deposited Mg
film. During the tests performed after the end of each cleaning operation we
have observed an increase in quantum efficiency (QE) in time. Then the QE
apparently stabilizes at a remarkably higher value. The study of this
phenomenon and its relation to chemical composition of the residual gases
of vacuum environment is important because it determines both the
achievable QE value and the lifetime of the Mg film based cathode.
Moreover, the stability of the QE at remarkably high values has been
revealed for a time scale of several days after each laser cleaning process, in
our vacuum conditions. The adsorption of reactive chemical species leading
to the lowering of the Mg work function is discussed
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
Antiresorption implant coatings based on calcium alendronate and octacalcium phosphate deposited by matrix assisted pulsed laser evaporation.
No full textThe integration of an implant material with bone tissue depends on the chemistry and physics of theimplant surface. In this study we applied matrix assisted pulsed laser evaporation (MAPLE) in order tosynthesize calcium alendronate monohydrate (a bisphosphonate obtained by calcium sequestration fromoctacalcium phosphate by alendronate) and calcium alendronate monohydrate/octacalcium phosphatecomposite thin films on titanium substrates. Octacalcium phosphate coatings were prepared as refer-ence material. The powders, which were synthesized in aqueous medium, were suspended in deionisedwater, frozen at liquid nitrogen temperature and used as targets for MAPLE experiments. The transferwas conducted with a KrF* excimer laser source ( = 248 nm, FWHM≤ 25 ns) in mild conditions of temper-ature and pressure. XRD, FTIR and SEM analyses confirmed that the coatings contain the same crystallinephases as the as-prepared powder samples. Osteoblast derived from stem cells and osteoclast derivedfrom monocytes of osteoporotic subjects were co-cultured on the coatings up to 14 days. Osteoclastdisplayed significantly reduced proliferation and differentiation in the presence of calcium alendronatemonohydrate, pointing to a clear role of the coatings containing this bisphosphonate on inhibiting exces-sive bone resorption. At variance, osteoblast production of alkaline phosphatase and type I pro-collagenwere promoted by the presence of bisphosphonate, which also decreased the production of interleukin6. The positive influence towards osteoblast differentiation was even more enhanced in the compositecoatings, thanks to the presence of octacalcium phosphate
Biofunctional alendronate–Hydroxyapatite thin films deposited by Matrix Assisted Pulsed Laser Evaporation.
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