1,720,954 research outputs found
Photostability and solubility improvement of beta-cyclodextrin-included tretinoin
No full textIn this work, we investigated the influence of β-cyclodextrin on the photostability of tretinoin and compared the photo-chemical stability of tretinoin, either in methanol or complexed with β-cyclodextrin, when exposed both to UV and fluorescent light. The physico-chemical characterization of tretinoin-β-cyclodextrin complexes, prepared by the freeze-drying process, using different tretinoin:β-cyclodextrin molar ratios (1:1 and 1:3), was carried out in solution by phase solubility studies, 1H-NMR spectroscopy, and in solid state by infrared spectroscopy (FT-IR); these analyses confirmed the existence of an inclusion compound. Solubility study results showed that tretinoin solubility was enhanced by inclusion in β-cyclodextrin as a function of increasing concentrations of β-cyclodextrin in aqueous solution at different pH values (i.e., 3.0, 5.5, and 7.0). Moreover, the complexation of the tretinoin with β-cyclodextrin effectively protected the photolabile drug and reduced the degradation of tretinoin induced by UV and fluorescent light, improving its photo-chemical stability in comparison with free drug in methanol. Indeed, dissolved tretinoin in methanol degraded very quickly and completely, while β-cyclodextrin- included tretinoin decomposition was delayed and, after 30 days under UV exposure, the percentage of remaining drug was about 20-25% (depending on the tretinoin concentration). The photodegradation of tretinoin in methanol under fluorescent light was slower: after 5 days of irradiation it reached a photostationary state and intact tretinoin remained constant (6.6%). In conclusion, the β-cyclodextrin complexation always led to a reduction of degradation, depending on the tretinoin:β-cyclodextrin molar ratio and on the drug concentration (0.2 mg/ml or 0.4 mg/ml)
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
Enhancing topical delivery of resveratrol through a nanozing approach
No full textResveratrol is a naturally occurring polyphenol with strong antioxidant and free radical scavenging properties, recently proposed as a therapeutic agent for skin diseases. In this study, we investigated the possibility of improving the dermal bioavailability of the poorly water-soluble drug resveratrol by nanocrystal technology. To this purpose, nanosuspensions were prepared by the wet media milling technique, using Poloxamer 188 or Tween 80 as stabilizers, and characterized by means of both solid state and morphological and dimensional studies. All analytical data demonstrated that neither a modification of the drug crystalline pattern nor the isomerization of the trans double bond were observed after the wet media milling particle size reduction process, which produced rounded and smooth nanocrystals with a mean diameter ranging between 0.2–0.3 μm. Resveratrol skin delivery from nanosuspension formulations was evaluated by the pig ear skin model via tape stripping. Results of the experiments showed that after application of nanosuspension formulations, higher amounts of resveratrol could penetrate the skin at deeper levels compared to drug coarse suspensions. The antioxidant activity of resveratrol in nanocrystals was assessed by the DPPH assay, which demonstrated that the size reduction process as well as the formulation compositions did not modify the drug antioxidant activity
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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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