1,720,976 research outputs found
Supramolecular structures prevailing in aqueous hyaluronic acid and phospholipid vesicles mixtures: An electron microscopy and rheometric study
No full textThe transport characteristics of hollow shells formed via self assembly of polyelectrolytes was the focus of this study. The shells were formed by layering on 5 μm diameter sacrificial cores that were subsequently dissolved in an acidic media. The effect of two polyanions was compared: polyvinyl sulfonate (PVS) and polystyrene sulfonate (PSS) along with two polycations: polyallylamine hydrochloride (PAH), and polydimethyldiallyl ammonium (PDDA). The number of polyelectrolyte bilayers was varied from 2, 4, and 6. The diffusion of fluorescein-isothiocyanate (FITC) labeled dextran was monitored over a period of days after loading times of 12, 36, or 60 h. Loading was also characterized using confocal laser scanning microscopy (CLSM). Two molecular weights of FITC labeled dextran, 4000 and 77,000, were utilized in this study. The choice in polycation results in the largest changes in wall permeability for the neutral pH tested. PDDA architectures produce a higher permeability than PAH structures. Loading of 77,000 MW FITC-dextran was observed in both the PVS/PDDA and PSS/PDDA structures
METHYLPREDNISOLONE ESTER OF HYALURONAN AS A DELIVERY SYSTEM: PROTEIN RESISTANCE, CELL ADHESION AND DRUG RELEASE
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Studies on coffee roasting process by means of nuclear magnetic resonance spectroscopy
Full text linkThe chemical composition of coffee has been widely investigated, focusing the attention both on main components and trace compounds. Most of these studies have been performed by using liquid and gas chromatography, eventually combined with mass spectroscometry. These techniques, although straight and effective, are time demanding due to the sample pretreatments. Here, we propose high-resolution-magic-angle spinning nuclear magnetic resonance spectroscopy (HR-MAS NMR), a system capable of acquiring highly resolved NMR spectra of gel-like and suspension samples. This approach allowed us to determine the chemical composition of coarsely ground coffee beans of two varieties: Arabica and Robusta. Variation of the concentration of relevant species was monitored as a function of roasting temperature, from green beans to completely roasted. The HR-MAS NMR tool demonstrated to be very powerful for quick chemical composition determination, opening up possibilities for novel applications of this approach in food quality control
CONFORMATION AND AGGREGATION OF METHYLPREDNISOLONE ESTERS OF HYALURONAN BY MEANS OF 1H PULSED GRADIENT STIMULATED ECHO NMR
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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
An evaluation of organic biostimulants as a tool for the sustainable management of viral infections in zucchini plants
Full text linkIn agriculture, new and sustainable strategies are increasingly demanded to integrate the traditional management of viral diseases based on the use of virus-free propagation materials and resistant or tolerant cultivars and on the control of insect vectors. Among the possible Integrated Pest Management (IPM) approaches, organic biostimulants have shown promising results in enhancing plant tolerance to virus infections by improving plant fitness and productivity and modulating metabolic functions. In this study, the combination of two organic biostimulants, Alert D-Max and Resil EVO Q, composed of seaweed and alfalfa extracts, enzymatic hydrolysates, and micronized zeolite, was applied on the leaves and roots of zucchini squashes, both healthy and infected by zucchini yellow mosaic virus (ZYMV). Four applications were scheduled based on ZYMV inoculation timing, and plant vegetative and reproductive parameters were recorded along with the virus titre and symptom severity. The modulation of the expression of specific genes potentially involved in
pattern-triggered immunity (PTI), systemic acquired resistance (SAR), and oxidative stress defence
pathways was also investigated. Besides increasing the general fitness of the healthy plants, the
biostimulants significantly improved the production of flowers and fruits of the infected plants, with
a potential positive impact on their productivity. The repeated biostimulant applications also led to
a one-tenth reduction in ZYMV titre over time and induced a progressive slowdown of symptom
severity. Genes associated with SAR and PTI were up-regulated after biostimulant applications,
suggesting the biostimulant-based priming of plant defence mechanisms. Due to the observed beneficial effects, the tested biostimulant mix can be an effective component of the IPM of cucurbit crops, acting as a sustainable practice for enhancing plant fitness and tolerance to potyviruses
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
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