1,721,015 research outputs found
INJECTABLE APATITIC CEMENT IONICALLY MULTI-SUBSTITUTED FOR REGENERATIVE VERTEBROPLASTY AND KYPHOPLASTY
No full textCEMENTO INIETTABILE APATITICO IONICAMENTE MULTI-SOSTITUITO PER VERTEBROPLASTICA RIGENERATIVA
No full textHuman osteoblast behaviour on as-synthesized SiO4 and B-CO3 co-substituted apatite
No full textThe functional behavior of synthetic apatite, commonly used as fillers or scaffolds, depends on
physical and chemical parameters, which vary in response to chemical substitutions and to thermal
treatments. The effect of silicon co-substituting with carbonate ions in the apatite lattice on the
properties of the as-synthesized powder and finally on human osteoblast in vitro behavior was
investigated. Dose-response curves of Si-free and Si-substituted carbonated apatites (namely CHA
and SiCHA-1 and SiCHA-2 with 0.88 and 0.55 wt % of Si, respectively) showed that SiCHA-1 had
toxic effect, whereas CHA and SiCHA-2, at worst, hindered osteoblast proliferation, but no toxicity
occurred. Subsequent experiments compared the effects of CHA and SiCHA-2 used at the doses of
0.3 and 1 mg/mL. After 7 days of treatment, both the powders stimulated cell proliferation and
protein content and inhibited alkaline phosphatase activity. However, SiCHA-2 slightly stimulated
osteoblast differentiation, as shown by higher calcium deposition, compared with CHA. The cell
behaviors were linked to the peculiar powder characteristics. The as-synthesized powder represents
the most critical system in terms of reactivity toward cells and can inform on the limits for
positively exploiting the characteristics of SiCHA powders in making bone fillers or scaffolds,
using no thermal treatment
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
High biocompatibility and improved osteogenic potential of novel Ca-P/titania composite scaffolds designed for regeneration of load-bearing segmental bone defects.
No full textRegeneration of load-bearing bone segments is still an open challenge due to the lack of biomaterials mimicking natural bone with a suitable chemicophysical and mechanical performance. This study proposes ceramic bone scaffolds made of β-tricalcium phosphate (β-TCP) and titania (TiO 2), developed from hydroxyapatite (HA) and TiO2 starting nanopowders, which exhibit high and interconnected macroporosity (>70 vol %). The scaffold composition was designed to achieve a synergistic effect of bioactivity/resorbability and mechanical properties suitable for load-bearing regenerative applications. The analysis of the morphology, structure, and mechanical strength of the scaffolds resulted in compression strength nearly twice that of commercially available HA bone grafts with similar structure (Engipore®). Biological characterization was carried out for human MG-63 osteoblast-like cells proliferation, activity, attachment, and viability. β-TCP/TiO2 scaffolds show high proliferation rate, high viability, and high colonization rates. Moreover, an increased activity of the osteogenic marker alkaline phosphatase (ALP) was found. These results demonstrate that β-TCP/TiO2 scaffolds have good potential as osteogenically active load-bearing scaffolds; moreover, given the high and interconnected macroporosity as well as the resorbability properties of β-TCP, these scaffolds may enhance in vivo osteointegration and promote the formation of new organized bone, thus resulting in very promising biomimetic scaffolds for long bone regeneratio
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
Iron-Doped Hydroxyapatite Nanoparticles for Magnetic Guided siRNA Delivery
No full textSmall interfering RNAs (siRNAs) are particularly attractive among the frontier drugs due to their high specificity of action, activity on disease-inducing genes, and small molecular weight, thus being one of the most studied agents for gene therapy. However, siRNAs are prone to fast enzymatic degradation in the bloodstream, as well as other limitations that challenge their clinical translation. Nanoparticle (NP) delivery of siRNA has been proposed as a potential solution, overcoming their intrinsic limitations. In this regard, the siRNA delivery by magnetic nanoparticles is of particular interest because, being susceptible to external magnetic fields, it may be guided remotely, maximizing transfection efficiency and minimizing side effects. In addition, magnetic NPs would also allow a theranostic combination of drug delivery, magnetic resonance imaging, and hyperthermia. In this work we have studied the uptake of a model therapeutic siRNA by iron-doped hydroxyapatite nanoparticles (FeHA NPs), which are known to have excellent biocompatibility and magnetic susceptibility. We discovered that FeHA NPs stabilized by citrate (Cit-FeHA NPs) uptake siRNA by adsorption quickly and with high efficiency (ca. 90%) without altering nanoparticles physicochemical properties or colloidal stability. SiRNA-loaded Cit-FeHA NPs are able to slowly release their payload, with a sustained release of 45 days without siRNA degradation. Our work is therefore the preliminary validation of the suitability of FeHA NPs for magnetically guided delivery of therapeutic siRNAs
- …
