1,720,999 research outputs found
Methods used to evaluate the peroxyl (ROO.) radical scavenging capacities of four common antioxidants
No full textDifferent methods that are used to measure peroxyl radical (ROO) scavenging capacity were used in model systems containing four common antioxidant compounds: ascorbic acid, cysteine, gallic acid and Trolox, a water-soluble vitamin E analogue. Five tests were performed, with differences in the method of peroxyl radical generation (lipoxygenase, azo-compound thermal degradation and spontaneous oxidation from a natural source of fatty acids) and in the addition of probes such as linoleic acid, crocin, fluorescein and electron paramagnetic resonance (EPR) by spin-trapping with a-phenyl-N-tert-butylnitrone. Significant differences were found in antioxidant reactivity, evaluated by dose–effect semi-logarithmic plots and EC50 values, and a possible explanation for these differences was explored. In assays in which ROO was generated by the azo-compound or spontaneous oxidation, gallic acid was the most powerful antioxidant. When lipoxygenase was used to produce ROO, ascorbic acid had the highest scavenging index, while cysteine and gallic acid had low levels of activity. Another difference was identified regarding the molecular probe: ascorbic acid and Trolox were the least reactive in the EPR system and azo-bis system with fluorescein, while in assays with crocin, these compounds had intermediate activities. Ascorbic acid and Trolox were the best antioxidants in an enzymatic-linoleic acid system, with a reciprocal ratio of 6:1, while adding crocin to the same system changed the reciprocal ratio to 2:1. A literature examination indicated that out of the antioxidant compounds tested, cysteine has the highest bond dissociation enthalpy, and this compound showed, as expected, low scavenging activity in three of the five tests in
this study
Chemiotropic behaviour of olive oil fly female (bactrocera oleae, G.Mel) on olea Europea, L
No full textAn interpretation is given of a number of observations on the chemiotropic behavior of Bactrocera oleae in connection with olive maceration water and the fly's return to the olive groves after the first summer rains. To this end, the headspace of both maceration water and leaf leaching water, simulating rainfall, were examined. In both cases, the presence of ammonia. which is generally known to attract fruit flies (Diptera, Tephritidae), was detected and, for the first time, in addition to other compounds that are inert for the fly, the presence of styrene was also detected. This aromatic hydrocarbon was found to be a strong attractant. It is shown that both ammonia and styrene are products of the metabolism of microbial flora present on the olive and leaf surface
Cooking influence on physico-chemical fruit characteristics of eggplant (Solanum melongena L.)
Full text linkPhysico-chemical traits of three eggplant genotypes ("Tunisina", "Buia" and "L 305") were evaluated before and after two cooking treatments (grilling and boiling). Different genotypes revealed different changes after cooking, with "Tunisina" showing a better retention of phytochemicals with respect to other two genotypes. The main physical phenomena were water loss during grilling, and dry matter loss after boiling. Chlorogenic acid, the main phenolic in eggplant, resulted higher in grilled samples, while delphinidin glycosides resulted more retained in boiled samples. Glycoalkaloids, thiols and biogenic amines were generally stable, while 5-hydroxy-methyl-furfural was found only in grilled samples. Interestingly, Folin-Ciocalteu index and free radical scavenging capacity, measured with three different assays, were generally increased after cooking, with a greater formation of antioxidant substances in grilled samples. NMR relaxation experiments clarified the hypothesis about the changes of eggplant compounds in terms of decomposition of larger molecules and production of small ones after cooking
Field trials of genetically modified tomato: fruit quality and productivity.
No full textIn the past twenty years, plant genetic engineering has been used to confer traits of both heuristic and applied interest to tomato. Genetic modifications have aimed to improve either the quality of the fruit and/or agronomical aspects of tomato cultivation. In open field trials, the novel genotype is tested under agronomical and environmental conditions similar to those used for production. Thus, field trials represent the most stringent test for any novel plant genotype, including genetically modified plants. In the following article, we discuss field trials performed with transgenic tomato plants that represent examples of different genetic strategies used in modern plant breeding. The examples chosen are genetic modifications related to three general aspects: (1) macro- and micro-nutrient content of the fruit, such as sugar content and beta-carotene content, (2) biological processes of either direct or indirect agronomical interest, such as parthenocarpy and resistance to disease, (3) features related to post-harvest and processing technology, such as fruit firmness and prolonged fruit vine-life. The discussion is focused on three main aspects: the genetic strategy used to confer the novel phenotypic trait(s), quality assessment of the genetically modified plant and fruit, and plant production. The results obtained confirm the value of plant genetic engineering as a means of improving tomato productivity and tomato products
Influence of genotype, location and year factors on quality and health promoting compounds of Rubus fruits
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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
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
Open field trial of genetically modified parthenocarpic tomato: Seedlessness and fruit quality
No full textBackground Parthenocarpic tomato lines transgenic for the DefH9-RI-iaaM gene have been cultivated under open field conditions to address some aspects of the equivalence of genetically modified (GM) fruit in comparison to controls (non-GM). Results Under open field cultivation conditions, two tomato lines (UC 82) transgenic for the DefH9-RI-iaaM gene produced parthenocarpic fruits. DefH9-RIiaaM fruits were either seedless or contained very few seeds. GM fruit quality, with the exception of a higher Β-carotene level, did not show any difference, neither technological (color, firmness, dry matter, °Brix, pH) nor chemical (titratable acidity, organic acids, lycopene, tomatine, total polyphenols and antioxidant capacity -TEAC), when compared to that of fruits from control line. Highly significant differences in quality traits exist between the tomato F1 commercial hybrid Allflesh and the three UC 82 genotypes tested, regardless of whether or not they are GM. Total yield per plant did not differ between GM and parental line UC 82. Fruit number was increased in GM lines, and GM fruit weight was decreased. Conclusion The use in the diet of fruits from a new line or variety introduces much greater changes than the consumption of GM fruits in comparison to its genetic background. Parthenocarpic fruits, produced under open field conditions, contained 10-fold less seeds than control fruits. Thus parthenocarpy caused by DefH9-RI-iaaM gene represents also a tool for mitigating GM seeds dispersal in the environment
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