1,721,065 research outputs found
Effect of aluminium exposure on the release of organic acids and genistein from the roots of Lupinus albus L. plants
No full textAluminum (Al) toxicity is one of the main factors limiting crop productivity in strongly acidic soils. Plant tolerance to Al toxicity has been widely studied even if the mechanisms involved in the plant response are yet not fully elucidated. White lupin is well known to release organic acids and flavonoids under nutrient deficiency, while less is known about its response to elevated Al concentrations. The aim of this work was therefore to shed light to the adaptive response of white lupin to Al toxicity, analysing the root exudate pattern. A pH buffer (MES) or inhibitor compounds were used in order to further investigate the mechanisms adopted by white lupin to release root exudates as response to Al toxicity. The results showed that not only organic acids but also phenolic compounds are involved in the response to elevated concentrations of Al together with the alkalinisation of the growth medium
Nitrate removal from polluted water by using a vegetated floating system
No full textNitrate (NO3−) water pollution is one of the most prevailing and relevant ecological issues. For instance, the wide
presence of this pollutant in the environment is dramatically altering the quality of superficial and underground
waters. Therefore,we set up a floating bed vegetatedwith a terrestrial herbaceous species (Italian ryegrass) with
the aim to remediate hydroponic solutions polluted with NO3−.
The floating bed allowed the plants to growand achieve an adequate development. Ryegrasswas not affected by
the treatments. On the contrary, plant biomass production and total nitrogen content (N-K) increased proportionally
to the amount of NO3− applied. Regarding to the water cleaning experiments, the vegetated floating
beds permitted to remove almost completely all the NO3− added from the hydroponic solutions with an initial
concentration of 50, 100 and 150 mg L−1. Furthermore, the calculation of the bioconcentration factor (BCF) indicated
this species as successfully applicable for the remediation of solutions polluted by NO3−. In conclusion, the
results highlight that the combination of ryegrass and the floating bed system resulted to be effective in the remediation
of aqueous solutions polluted by NO3−
Caratterizzazione fisiologica e molecolare del rilascio di essudati radicali in piante di melo sottoposte a stress nutrizionali
No full textEffetto della disponibilità di zolfo sull’assorbimento di nitrato e di solfato in barbatelle di vite allevate in soluzione idroponica
No full textInfluence of different trap solutions on the determination of root exudates in Lupinus albus L
No full textWhite lupin is very often used as a model plant for root exudation studies due to its capability to release huge amounts of organic acids and flavonoids. The complex nature of these organic compounds makes not only their analytical determination difficult but also their extraction from soil samples. For these reasons simplified approaches, as hydroponic-based systems are widely used to study the root exudation. Therefore, the composition of a trap solution is crucial to limit artefacts causing over/underestimation of exudation rates and/or a biased molecular composition of the collected compounds. The present study was aimed at assessing the influence of different trap solutions and collection times on the quali- and quantitative root exudation pattern of white lupin (Lupinus albus L.) grown under phosphorus (P) and iron (Fe) deficiency. Our results suggest that, in works aimed at studying root exudation processes, water is the most effective trap solution to collect the exudates like organic acids and flavonoids, especially in short time (e.g. 2 h). For longer times, low concentrations of Ca could be helpful to limit osmotic stress and possible passive leakage and/or diffusion. The use of bacteriostatic compounds as NaN3 and Micropur bias the results, due to interferences either with the metabolism or inhibition of the exudation processes, especially in the case of flavonoids such as quercetin. Also, the use of a pH buffer solution like 2-(N-morpholino)ethanesulfonic acid (MES) should be avoided for its undesired interferences with the release
Forme di ferro presenti in frazioni umiche a diversa solubilit : caratterizzazione chimica e valutazione della disponibilit da parte di radici di piante di cetriolo
No full text
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
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