1,720,963 research outputs found
Ozonated Sunflower Oil Embedded within Spray-Dried Chitosan Microspheres Cross-Linked with Azelaic Acid as a Multicomponent Solid Form for Broad-Spectrum and Long-Lasting Antimicrobial Activity
No full textMulticomponent solid forms for the combined delivery of antimicrobials can improve formulation performance, especially for poorly soluble drugs, by enabling the modified release of the active ingredients to better meet therapeutic needs. Chitosan microspheres incorporating ozonated sunflower oil were prepared by a spray-drying method and using azelaic acid as a biocompatible cross-linker to improve the long time frame. Two methods were used to incorporate ozonated oil into microspheres during the atomization process: one based on the use of a surfactant to emulsify the oil and another using mesoporous silica as an oil absorbent. The encapsulation efficiency of the ozonated oil was evaluated by measuring the peroxide value in the microspheres, which showed an efficiency of 75.5-82.1%. The morphological aspects; particle size distribution; zeta potential; swelling; degradation time; and thermal, crystallographic and spectroscopic properties of the microspheres were analyzed. Azelaic acid release and peroxide formation over time were followed in in vitro analyses, which showed that ozonated oil embedded within chitosan microspheres cross-linked with azelaic acid is a valid system to obtain a sustained release of antimicrobials. In vitro tests showed that the microspheres exhibit synergistic antimicrobial activity against P. aeruginosa, E. coli, S. aureus, C. albicans and A. brasiliensis. This makes them ideal for use in the development of biomedical devices that require broad-spectrum and prolonged antimicrobial activity
Oxidative stability of long-chain fatty acids with different unsaturation degrees into layered double hydroxides
No full textNowadays, there is increasing evidence that the intake of essential fatty acids (FAs) and oleic acid has high nutritional importance. However, the vulnerability of these FAs to oxidation deserves special attention. FA oxidation may be avoided or delayed by intercalation of its anionic form in inorganic matrices as layered double hydroxides (LDH). Thus, the aim of the study was to evaluate the protective effects of MgAl LDH towards oleate (O), linoleate (L) and α-linolenate (Ln) degradation. The incorporation and the loading of different FAs in anionic form in LDH was determined by X-ray diffraction and thermogravimetric analysis (TGA), respectively. In order to study the selectivity of LDH towards the FA, the inorganic solid was equilibrated with a mixture of O, L and Ln (1:1:1). TGA and gas chromatography showed that Ln was preferentially intercalated. Free FA (FFA) and intercalated FA (IFA) were heated at 40◦C in the dark and then analyzed weekly for a maximum of 42 days. Their oxidative stability was evaluated by monitoring the primary and secondary oxidative compounds. The volatile compounds were determined by solid-phase microextraction, coupled with gas chromatography–mass spectrometry. Peroxide values were higher in FFA samples than in IFA samples, such as hexanal and trans,trans-2,4-heptadienal % contents. The results showed the potential of LDH intercalation for FA preservation from oxidative modification
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
Solid phase adsorption of anthraquinones from plant extracts by lamellar solids
No full textSolid phase extraction is nowadays a well validated and powerful technique applicable to complex matrices like plant extracts and phytocomplexes. This process provides concentration and/or purification of selected secondary metabolites from these matrices for subsequent analysis and isolation. In this research article sixteen lamellar solids, comprising layered structures (hydrotalcites, zirconium phosphates, magnesium hydroxide), magnesium oxide, and the phyllosilicates talc and bentonite were investigated for their capacity and performance to selectively adsorb five naturally occurring and widespread anthraquinones (aloe, aloe-emodin, rhein, chrysophanol, and physcion) contained in three ethanolic extracts of well known plants with purgative effects (frangula, senna, and rhubarb). Ethanolic solutions of extracts from these species were vigorously magnetically stirred with fixed quantities of each solid support at room temperature for 1 h. Subsequent HPLC analysis, coupled to photodiode array detection, revealed that, among the solids tested, the hydrotalcite zinc aluminum oleate and magnesium aluminum azelate and magnesium oxide were largely the most effective to this concern allowing to recover anthraquinones (all or some) in good to excellent percentages. Another interesting result was the selective and total removal of rhein by some sorbents from senna and rhubarb extracts. Sorbents were also recyclable and could be re-used to accomplish additional steps without appreciable loss of adsorption capacity. The application of the title solid inorganic and mixed inorganic/organic supports for the selective adsorption and concentration in the solid phase of anthraquinones from commonly used laxative plant species is reported herein for the first time
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
Solid Phase Adsorption of Emodin on Hydrotalcites and Inorganic Oxides: a Preliminary Study
No full textSolid phase extraction applied to plant matrices is nowadays a well validated technique allowing the concentration and purification of selected secondary metabolites for subsequent analysis. In this short communication we screened the efficiency of 16 selected solid supports including layered structures (hydrotalcites and zirconium phosphate), magnesium oxide and hydroxide, and finally the phyllosilicates talc and bentonite for the selective concentration of the anthraquinone emodin from raw solid extracts of Polygonum cuspidatum Siebold & Zucc. (sin. Reynoutria japonica Houtt.) (Polygonaceae), commonly known as "Japanese knotweed". An ethanolic solution of sample extract from this plant was vigorously mixed with fixed quantities of each solid support. Subsequent HPLC analysis, coupled to photodiode array detection, revealed that, among the solid supports assayed, the hydrotalcite zinc aluminum oleate and magnesium oxide were largely the most effective to this concern. Both were able to extract emodin from the raw extract in percentages of 81.5 % and 92.4 %, respectively. The application of the title supports for the extraction and concentration in the solid phase of anthraquinones from raw plant extracts have been reported herein for the first time
Pre-concentration of capsaicinoids from different cultivars of Capsicum annuum after extraction in heterogenous mixtures
No full textCapsaicinoids capsaicin, dihydrocapsaicin, nordihydrocapsaicin, and homocapsaicin from extracts of twenty-two cultivars of hot pepper (Capsicum annuum L.) were analyzed after treatment of the extractive solutions with a panel of nineteen heterogenous supports (hydrotalcites, lamellar solids, and phyllosilicates). Among the hot pepper varieties, the one named Big Black Mama Mustard exhibited the highest concentrations of the selected phytochemicals after a preliminary maceration and thus was chosen to test the efficiency of the solid phase extraction step. The hydrotalcite magnesium aluminium azelate and bentonite performed as the best sorbents in terms of extractive yields of all capsaicinoids herein under investigation, providing percentages ranging from 73.5 % to 91.6 % and 68.4 % to 70.8 %, respectively. The solid phase extraction of Capsicum spp. by hydrotalcites is described in the present study for the first time in the literature. Data reported in this study may be of help to set up convenient industrial processes to obtain nutraceutical and food additives enriched in the title capsaicinoids
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