1,721,077 research outputs found
L'importanza della nanotopografia per le interazioni in vitro cellula-superficie
No full textLo studio delle interazioni cellula-superficie in vitro è di fondamentale importanza
per gli aspetti applicativi di un biomateriale. L’adesione cellulare (eucarioti/
procarioti), la migrazione, la proliferazione e la differenziazione sono
processi biologici che sono influenzati sia dalla composizione chimica che dalla
topografia della superficie del biomateriale impiegato. In ambito medico, l’applicazione
progressiva di superfici micro-nanostrutturate ha acquisito crescente interesse
al fine di poter migliorare la citocompatibilità e l’integrazione tissutale. È
quindi di grande interesse sia la comprensione delle interazioni cellula-superficie
sia l’utilizzo di nuove tecniche biofisiche che consentano di determinare quantitativamente
le interazioni a livello dei singoli componenti molecolari coinvolti
nel processo di interazione. Per questo motivo i fattori fisici sono importanti, al
pari di quelli biochimici, per determinare la risposta cellulare ad una specifica
superficie.
In questo capitolo, cercheremo di: I) definire i meccanismi principali delle interazioni
cellula-superficie in vitro, soprattutto a livello di nanoscala per effetto
di nanoprotrusioni, nanocavità e nanoscanalature; II) illustrare le recenti tecniche
biofisiche che hanno aperto nuove prospettive nell’ambito delle funzioni biologiche
e introdotto un nuovo elemento di determinazione quantitativa in questo
campo
Novel biodegradable and biocompatible poly(butylene cyclohexandicarboxylate/diglycolate) random copolyesters with adjustable properties for controlled drug release
No full textINFLUENCE OF ELECTROSPUN POLY(L-LACTIC) SCAFFOLD MORPHOLOGY ON IMMUNE RESPONSE
No full textElectrospun bioresorbable polymeric materials are widely used as scaffolds for tissue engineering applications. However, up to now their potential effect on the immune system has not been carefully examined. Indeed, macrophage interaction with implanted scaffold materials might lead either to cytotoxic inflammation or to constructive remodeling. In this study, in vitro evaluation of the immune response to electrospun poly(L-lactic acid) (PLLA) scaffolds with different fiber diameter and alignment has been performed by using murine macrophage cell-line RAW 264.7. Scanning electron microscopy observations showed the influence of scaffold surface topography on the macrophage morphology. In comparison to PLLA films and microfibrous scaffolds, the nanofibrous scaffolds showed less reactivity in terms of cytokines and chemokines secretion after 24 hours
Thermal stability improvement of blue colorant C-Phycocyanin from Spirulina platensis for food industry applications
No full textC-Phycocyanin (C-PC) is a blue pigment in cyanobacteria, rhodophytes and cryptophytes with potential
use as a value-added food colorant. Its stability was studied by examining the thermal degradation reactions
in a range of temperature (25-80 ◦C) before and after the addition of selected edible preservatives.
The natural protein crosslinker methylglyoxal does not stabilize significantly C-PC whereas addition of
honey or high concentration of sugars greatly diminish the blue color degradation occurring when C-PC
is exposed to high temperature.
Data show that the sugar preservative effect on the C-PC blue color is related to the final concentration
of sugar added rather than the type of sugar. For this reason the best preservative was found to be
fructose, which is the most soluble sugar among those tested, at saturation concentration. Exploratory
sterilization studies have been carried out with six blue/green fructose syrups made by mixing C-PC with
the natural yellow pigment Carthamus tinctorius. Both after a “low temperature” and a “high temperature”
sterilization procedure the syrups remain clear and maintain their bright color with only partial blue
color degradation. After the sterilization process, the syrups were monitored for two months, in such
observation period the loss of blue color is minimal
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
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